Powered combat exo suits are not field feasible until there is a quantum leap in current battery and/or micro generator technology.
Until then, the most likely earliest combat exo suits may look a bit like a throwback to medevil knights, where you have a rider with a powered suite riding into combat on a 2-4 legged mechanical mount.
The mount will be the primary power source for the rider's suit, which only need enough internal power for a few hours.
The mount gets the operator to and from mission sites at far higher speed than what even would be possible with a powered exo suit. Operator can then carry out the mission without the extra bulk and reduced mobility of having to internalise a power source able to keep the suit functioning for days or weeks with current and even next gen power supply tech, and finally exfil using the mount.
You could also add charging stations to APC/IFVs and helicopters etc for mass general purpose employment, but the main issue (aside from cost) would be keeping the suits charged during a prolonged engagements.
But for general frontline combat applications, if there is a big enough breakthrough in wireless charging technology, mass deployment of combat exo suits might well be feasible (if there is a budget for it - I'm not sure even the US can afford to issue those suits en mass, so SpecOps seems like the most likely initial users, which limits you to mobile power generators).