what happens if this venture flops? will it be a major drain on NISA?
A drain yes...a major drain...probably not, since NISA is not Mass producing these titles, I think they are aware of the possibility of a flop & thats why they are only selling their anime online and not in Brick N morter stores.
at the very worst, it'll just make them decide to not do anime again.
But if it does well, hopefully they will start acquiring 4 or so titles every year. (And hopefully expand to manga & light novels as well...so we can get the rest of the Disgaea publications as well as the toradara LN's...)