I think it probably does cannibalize a bit of same day voting, but keep in mind the decline in AA turnout we’ve seen so far will also likely occur on election day as well, more than offsetting it. And if trump picks up net 50-100k votes on Ind more than Romney, easily could be near double digits (In 2004 when Obama wasn’t at the top of the ticket, Bush won by 12% here and he wasn’t picking up nearly as many < $75k as Trump will).
The margin of victory may be driven by the unaffiliated voters that are turning out 25-30% above the 2012 race. I also think Trump will do a little better among the AA population. I have had several black persons tell me their parents (especially fathers) would not vote for a woman. I’m thinking Trump may win by 4% but you may be right.
I suspect the Republican in-person early voter over-performance will continue to grow. Yesterday was the first day for the expanded number of polling places and many of these new polling places are in the suburbs. I live outside Winston-Salem and our polling place was packed yesterday.