I think the top brackets may drop 10% or so in 2017. That said if PGPM PPS goes to the level I think it will most of us will likely hit the 35%+ tax bracket, based on 2016 rates. A nice problem IMO:)
Under current tax rules if you've been holding 1 year or more, and you're tax bracket is 25% to 35%, then you will only pay 15% on your capital gains. If you're in the highest tax bracket, 39.6%, you'll pay 20% on your long term capital gains. See "other investments" column here: