Two things that improve the chances that somebody other than AA and/or LDR will play:
* even if they haven't necessarily gotten a lot of reps in practice, by this point in the season the freshmen QBs have accumulated 12 games worth of film study etc. Theoretically, they know a LOT more now than they did 2 or even 7 games into the season. More knowledge = less risk. (Still could be very high, but it's less than it was.)
* during the regular season, players are allowed 20 hours of football time per week, and part of that is devoted to putting in the game plan for the upcoming opponent. We have 80 hours of football time before the next game.
I can't speak to the mindset of the coaches however. Nor to how the other freshman or potentially incoming QBs would react, if either Franks or Trask is named starter for the bowl game, which would implicitly also make him the default leading candidate to be next year's starter.
On the flip side, if you were in the shoes of Trask or Franks, knowing Allen is coming in and Stidham is a decent possibility, would you trade a future year of eligibility for the chance to start this bowl game and possibly lock-in your status as the front-runner for next year?
One of the interesting things about how SOS uses his quarterbacks ... yank 'em if they're not doing well or what he wants, and try somebody else ... i.e., exactly how coaches handle every other position on the team ... is that the choice of "who's the starter at QB" isn't quite as consequential or near-immutable as it seems to be for McElwain and Nuss. Some corporate CEO was recently quoted as saying something to the effect of "Having a Plan B is preparing for failure." Our coaches seem to have that mentality on QBs.