It's very hard to project upgrade times now with the new TA. Too many unknowns.
How many will leave in the next couple years? Probably not many, but there will always be a slow trickle of old guys leaving.
How many will wait to upgrade on an APU airplane? It might become more prevalent with a 39 month seat lock now.
How many with airline or military pensions (or just don't need the money) will just choose to stay an FO for the relative seniority? There's been a couple recently that bid NJI FO and they could have held NJA Capt.
I certainly don't have the answers to these questions, but I think it will be interesting to watch for the next couple years.