Improvements from year-to-year..

I hate to say it, but "it depends."

There's some essential data that you've left out:

1.  What races are you training for?  Sprint? Oly? 70.3?
2.  What races are you training for?  Local (small), regional (med-large), national (top competition)?
3.  How have you been training?  Using a plan?  Have a coach? 

All of this information will have a bearing on if you're going to be podium-worthy in the next couple of years.

Like I said, it all depends.  The more effort you put in (and the smarter you train), the faster your splits will get.  There's too many variables to say you will decrease x amount per year.  Just go out, do your thing and let the chips fall as they may.

It is really hard to say with such low training vollume posted on BT and only a few months.  Keep records for year one, average your yearly pace, then do the same for year 2 and compare.  Getting 30 seconds faster on the run, 1-2 miles faster on the bike and 10 seconds faster pace on the swim seems reasonable in 1 year's time following a plan for you.  You could probably make the same gains the following year.  But with no information.... it is just speculation.  So set some goals, pick a plan and have fun.   

Yes, I'm a total newb, did a 16 week prep for my first race, and then after my last race had some personal things to deal with and had a pretty low august and September, but hopefully between now and January I can average 5-7 hours/week total (if the weather is nice get in about 8 hours total or so by getting in some longer bike rides).  If all things go smoothly, I would like to be doing 25-30mpw(depending on how much road/trail I do), 6 hours on the bike (I ride lots of different terrain, so mileage totals won't match what a roadie would expect), and about 6,000 yards/week in the pool by next april.  This should be attainable while following the 10% increase.  I followed one of the free plans at first, but it's not that hard to figure out the gist of the plan and tailor one specifically for me. It seems like a lot right now, but I've got 5 months to get there.  (then year 2 is kind of up in the air right now, but it seems like I won't need to increase my volume much from the 10-12hr/week range)

If I'm going to do something I'm going to put in the effort

I race xterra's, so they're pretty close to OLY distance, some longer, some shorter. 

Looking at your last run only (8:30/mile pace for 5 miles), which probably means you can run about a 46:30 open 10k (just an educated guess). IMO, assuming that you're out of the early period where improvement comes very easily, dropping that run pace by 10% (41:50) on 5-7 hours/week/year of tri training is definitely on the high end of what's possible. Droppng it another 10% to 37:40 will be MUCH harder as minutes are hard to come by once you're under 40:00.

But that's the beauty of training. If your goal is to drop 10% a year and you only make 5%, you've still had great success. And you may just be poised to burst to the other 5% improvement quickly. In my experience it's hard to predict improvement and it often comes in bursts. IMO, it also often shows up in different ways than just a faster 10k time such as, faster recovery allowing you to run the same splits more often.

I totally agree.  I have had some slow and steady gains in running over the past 2 years of running around 100 miles per month, more when building for longer races (140), but it is really this last month after my first IM that I am totally excited about my running and seeing some really big improvements.  I started at like 11:30 mintues per mile two years ago and now I can hold an 8 minute per mile pace for 10 + miles, faster for shorter distances, with half mile repeats at LT around 6:30-6:45.  Granted this is not fast when looking at podium paces,  but I have moved from BOP ish to MOP ish.  But more importantly I am off the couch and having fun.  Pick a duable amount of time for your routine and then just use it well and consistently.  You will be amazed at how much a 5am workout and noon workout can add to your free time in the evening.     

You should be able to improve a lot if you're willing to put in the work. If you're fairly new to the sport, I'd expect at least 2 years of solid gains before you even have to start getting really serious about training.As for 10% per year, that'll be tough after the 1st year. For BOP athletes, 10% improvement is realistic for the motivated, but for podium-level athletes who have generally hit diminishing returns, 10% is more than several classes of improvement.I wouldn't worry about your rate of improvement too much though. Train hard, and the satisfaction of breaking all your PRs through hard work and planning will be far in excess of any conception of your margin of improvement. I do think that most people do have the ability with serious training to be contenders for an AG podium spot, and almost definitely so in small local races. Keep in mind that serious training is pretty heavy duty, and underestimated by most AGers new to the sport - 14+ hrs/wk of structured training per week is not unusual and may even be on the low side for AG winners in the younger categories, even for local races.

yeah, I was realizing how much of a per/mile improvement I was talking about today as I was sitting and thinking while on a stupid stationary bike.  I have already dropped 30 seconds off my training pace from what I was doing when I was running 2x/week, so if I can hold this current pace while I get up to some good longer runs I'll consider the off season a success.  But doing that consistently is going to take some serious work.  Also, I have yet to get a run split to match even my training pace, so with some better bike fitness (and better pacing) the run will get faster

Also the 5-7 is a minimum estimate per week up until the new year since I'd like to get in 4-6 hours of biking alone, and 2+ running, and get back to at least 2 hours of swimming/week, but with all this rain looming overhead I didn't want to get too far ahead of myself.