If you bought to definitely flip I think there will be two main frenzies on ebay - when they are first received, from those who missed the issue. Then when the first graded ones come in - 70s will be what everyone wants, as Steve says. You'll probably make more on a 70 than the raw coin but not guaranteed - like Numi says don't be greedy, and if you like the prices in the first round of sales OK you may miss a premium after grading but perhaps you'll be more than happy at what they go for initially (plus it's far less work)?
I think what @sovereignsteve means is if you're going to sell anyway do it sooner rather a year or two down the line - there is hype for these now but collectors may not be very interested in the future. I like this one but if there are similar releases this year and carrying on in future (especially repeating the 'trick' of the plain edge) I can see the appeal on this one diminishing - plus some collectors like Steve aren't interested to begin with.