With the embargo dropping we now know what the new Great Weapon Master feat does: +1 to Strength, you can add your Proficiency Bonus to damage rolls of ALL attacks with a heavy weapon made with your Attack action, and if you kill a creature with a melee weapon, you can make an additional attack with a bonus action.
This bonus damage more than makes up for the loss of -5/+10 features, GWM is now a half-feat AND it can be used with longbows and heavy crossbows. Considering this, the buffs to fighter and barbarian and weapon masteries, melee two-handers are in an incredible place power-wise.