Great Weapon master + barbarian is already very close to what you're suggesting. You get double damage for a -5 penalty to hit, which isn't prohibitive if you're raging and have advantage on all your attacks. Throw in some polearm master and you're all set.
If they keep those feats the way they are in the playtests, I don't see how it's at all likely that you will see many fighters that aren't using that combo. Threatening reach on a heavy double weapon that only needs one enchantment? Sure, sign me up! It would be absurd to use a greatsword when you can get reach + possibly 2 more attacks. And it would be even more absurd to dual wield d6 weapons for 3 attacks, when you could get 3 or even 4 attacks at 1d10 + mods and the last one at 1d4 (+mods if you can apply them to offhand).
The next question becomes, is it better to use your reaction to attack a rushing foe when they provoke, or to use something like Protector and mitigate incoming damage instead? I guess it depends on your AC and their expected average damage vs your own. If you would deal more damage with an attack on the approaching foe than you would reduce by imposing disadvantage, then you should come out ahead, unless you don't because your HP get depleted before your own turn to retaliate. In theory you could do only 1 damage per round, as long as you have a super high AC and impose distadvantage, it should be near impossible to get hit. As long as you win in the end, which is what I believe most fighters care about.