Lady Gaga is 32. When did she have time to "get off at Saratoga for the 14th time"? If anything, she should play Sarah.
Megan Mullally would be perfect as Adelaide: funny and sympathetic.
Perhaps some genius will find a way, but I don't see how a remake works except as a period piece. With Indian casinos, the whole world of gambling is so different today, as are "gangs".
But I'm with bk. I don't see this happening as a feature film. It would work better as some network's "live" special, though I doubt it has the proper appeal to the "desired demo". Gaga might help with that, if she so desired.