My duaghter's only 2 - but, typical alcoholic that I am, yes, I have already thought (i.e. worried) about this.
I feel in a bit of a lose-lose situation, to be honest - obviously it would be preferable for her to take after her mother (who is in no way alcoholic) but I selfishly worry I won't understand her as I'd like to if she's a civilian!
Also, a big part of me thinks that either I was born an alcoholic or couldn't help becoming one - so it follows that, if my daughter takes after me, there's very little I can do about it.
My plans, such as they are, are:
hope really hard that, if she is an addict, she picks something legal and with a long fuse (alcohol or gambling, basically) - addictions's bad enough without factoring in crime and the various powders and potions the cut heroin with
continue not to drink myself so that, if she is willing to take it, there is an example for her that one can be happy and normal(ish) without drinking
answer her questions as honestly as I can, without giving her nightmares
not encourage her to drink in a "oh, you must get pissed at least once or you haven't lived" way but not ban it either
if she does turn out to have a problem, be available for her and, when the time is right, try to 12th step her
It's a bugger, eh? I try to keep that in the day, too - or, as you put it, we'll cross that bridge when we come to it.