If he doesn't gives what is expected of him about Bitcoin, heaven will not fall, the market is going to correct itself but the damage will be minimal. The people that are in for long term will continue to hold until one person that finally did will come and makes that approval for Bitcoin. Usually, things doesn't just approval like that in a country, it takes time. A bill has to be signed and pass and every other people in the house has to approve it.

What some people doesn't understand yet about this is that when a bill is sent to the senate, they takes them based on how they will want to evaluate it and see the effect. It's the duty of the president to write a bill and ask for its approval; if that's alone is done then rest assure this market will go beyond what we expected, even if it doesn't get pass now, it will in the future. However, since the Republicans dominate the house, the bill approval is very likely.