Measuring Cycling performance

Realistically and conservatively I'm going to say probably not, at least not from what I'm seeing in your logs. You can certainly make some advances, but if you're talking about doing the bike in 2:40 you probably need to have a bigger base than what you've built so far.

Stranger things have happned, though.

How flat are your rides?  How technical?  How much head/tail wind do you have?  How hot/humid is it?  How hard are you riding?  How about the same for the HIM course?

FWIW, my training paces were generally in the 16-19mph range during the last 2 seasons.  The HIMs I did were in the 20-21mph range.  My home routes are generally fairly hilly while only one of the HIMs had any real hills with which to contend.

I hadn't checked out your logs before.  Nor seen you HM pace. 

IMO, you can do 20-21 by this summer just putting in some more miles.  You've clearly got the engine, but need to learn to apply it on the bike more.  That said, and echoing some other advice, how fast you end up riding should not be dictated by some target mph pace.  You need to go by effort level (power, HR, RPE, whatever) so that you leave yourself with enough reserves to put up a good run afterwards (for you, probably sub-1:40 assuming reasonable conditions).  Whatever mph that gives you on race day is what it is.  Speed itself is generally not a very good pacing device on the bike because of all the external influences (the point of all the questions that I asked).