I think with covid-19 it could mean they are nearing the end of a final release which they will surely drag out for as long as they can. Or WB might postpone things and or break it up in tinier bits, which is why I don't necessarily think a KP3, 4 or even 5 is that crazy. In theory that is, with 3-4 characters in each pack over the next 2 years. That gives NRS time to get the VAs back in the booth for one last time. I think future games are going to be delayed in any case, so WB might actually have given NRS the go ahead to do more than they initially planned. They have nothing else much on their hands in terms of another IP or Injustice 3 given motion capture and all that is not possible, so a few more extra characters wouldn't be totally out of the question. Especially given the success of Aftermath, KP2 and any content coming out for games at this time. Sales are through the roof!
A full on story expansion is however still unlikely given the restrictions, in my opinion. I don't even know how they'd do it. It's clear they've done the latest recordings remotely, which is why there's re-used lines. To think Aftermath 2.0 or any story expansion was fully done before covid-19 is crazy and how would they go about finishing it now if they've started it? It could be scrapped, surely and probably is if they ever planned in. In any case, any leak that claims a story mode expansion is coming and or a character that was worked on, full rendered, perhaps even with a moveset or whatever now having been replaced should raise serious red flags.