I appreciate that but I think that there is a big difference between the problem of whether future life is important and whether you are responsible for the good felt by a life that your actions produce. For instance, I don’t think that I can be responsible for the good felt by my future children (they are indebted to me for giving them life), but I still think that my future children have moral importance and I should do things now to make their lives better.
When applied to veganism I think it’s pretty clear that I can’t take responsibility for whatever pleasure domestic animals whose existence is due only to the demand that my consumption creates. And, because of that, I’m just not really convinced by arguments that my meat consumption is very defensible. I think it’s almost certainly a moral flaw of mine but I haven’t built the self-preservation to stop eating meat. I like food culture too much and while that may make my life better it doesn’t take the blood off my hands.