He'd have to be at least 50 first. (And the AC iHeart is relatively new, the Wikipedia page hasn't been updated yet.)
He's pushing 40 now so that wouldn't be too many years away.
Actually Seacrest is already 40 (birthdate Christmas Eve of 1974.) He's well enough known and established that if Premiere wanted to launch a regular AC show he probably could do it, especially as the music therein has actually gotten less "soft" lately and closer to the Hot AC and CHR that he already does.
In fact I sometimes wonder if the Hot AC subformat is really needed anymore as it's become less distinguishable from the regular adult contemporary stations, at least those that emphasize the "contemporary." The grand exception to this is late in the year when so many AC stations go mainly or entirely to holiday music.
Right now HAC is more in tune with CHR. Listen to the two editions of AT40 and you'll hear almost all the same songs in it and in many cases near the spot they are on the other.
Yes there will always be a need for HAC and AC. HAC plays a large percentage of the same stuff you hear on the average top 40 station. But it does not include the hip hop or heavier stuff. There are also the HAC stations that play more from the last 2 or 3 decades in addition to current music.
AC is more slow and soft music from now as well as the past 30-40 years.