My bet is: no.
Aside from age, here are your three issues:
1. "Same weight" as high school is a bit deceptive - sure you might see the same number on the scale but where that weight is distributed and it's composition is probably completely different than yourself at 18-20yo. This makes a difference.
2. Cycling - I think this has minimal help to runners particularly at middle distances (unless it is being done as a supplement to a running regiment). As previously mentioned, you might have maintained/developed your cardio but you've more than likely crushed your form/speed (which is obviously vital for middle distances). When I see a competitive runner moving to the bike as replacement for running (aside from injury recovery) a few days a week, my first thought is "they're done with serious running". BTW, I don't think this is the case when runners add/replace running with swimming/aqua-jogging/elliptical/rowing. Something about riding a bike quickly (15-22mph) down the street while covering mass distances (30-50+ miles) at less-than-running-effort does something to the brain that reduces running enthusiasm (just my opinion).
3. Speed - again, age aside, unless you were an absolute speed-demon in high school (naturally in the mid 20s, low 50s), then that boat might have sailed. Speed declines as you age regardless: if you didn't start atop a mountain, you might already be at ground level.
Don't go to a track and try to rip a sub 60sec quarter. Go to the track and try to run a 64-65 and report back... you'll need to repeat that x4..!
Regardless, good luck - please prove me wrong!
-Krispy