No one is going into Syria Obama and the U.N. will give the standard talking points this is unacceptable we condemn this all options are on the table and then forget the whole thing.
The hesitant approach towards Syria (not only from USA) is related to money, which will be needed to restore order in Syria after Assad has been either killed or captured.
"Military assistance" to FSA will increase the overall costs with them joining the Syrian Army in the destrution of Syria. Syria already looks pretty much destroyed. After all, this country needs a future otherwise it will be a breeding ground for sustained chaos in the region, and the Syrians don't have the Oil (like Iraq) to self-finance the reconstruction.
For delivering heavy-weaponry to the FSA it doesn't need Obama or the USA, but the SNC/FSA's supporters didn't give them these weapons also. If Obama wants to involve himself in this issue this will be no Lybian-style aircover for "rebels". The Syrian opposition is also an incompetent and disunited bunch of people, and there are some elements USA disagrees with. When you kill or capture Assad yourself, you are also dictating the terms and you're the kingmaker. I see this ending up into an intervention by USA and a few Nations very likely.