You are taking it too literally. A tank would easily crush a guy in power armor, between the rain of machine gun fire, and the canon.]It replaced tanks, because tanks used a lot of fuel, they were large, so that makes them less manueverible and harder to transport.
By 2077, the gas prices are $1450 per gallon and $8500 per gallon of premium.Tanks would be rather expensive to run.
It has been said.Fuel was running out and tanks use alot of fuel.Power Armour lets one man pretty much become a walking tank.Tanks svck in urban warfare and China has alot of really big cities. An army of men in suits that turn them into walking tanks would to much better in urban warfare then tanksI doubt tanks were completely removed from the battlefield but would have been reduced to nothing but mobel artillery.
But wouldnt they be running on a nuclear reactor like the cars and... everything else?
Im not saying power armor is worse then a tank, because I agree, conceptually they are an amazing piece of tech. But again, they practically can not stand up a tank toe-to-toe. A single tank round on a power armor user, never mind if the armor can take it, but the person inside would have all his bones shattered from the shere force trying to be absorbed. Conversly, a power armor user couldnt realistically weild much more then a fatman or missile launcher to combat a tank.
Being used along side one another, yes, I can see that. That is why in reality we don't use APCs in place of tanks, because tanks have a heavy hitting gun and vastly superior armor. They are designed specifically for taking on big things.