The suspension of progression in Portal is supposed to be temporary. This was a big selling point for this game so I can't see them abandoning progression all together in that mode. ....or solo / coop for that matter. I'd imagine they are trying to wrap their heads around a system that can identify exploitation of this mode for XP farming so they can implement a solution.
What gets me is that they said they had one in place to catch cheaters and yet it was something people were easily able to do. DICE is able to see how people progress so it would be obvious if there was a spike in activity showing "unnatural" XP gains within a period of time, etc. I don't get why they didn't catch all of this when it happened. IMO, either the system they created didn't work, wasn't equipped to handle how people exploited Portal or was not implemented for the early release.
It bums me out that BF2042 doesn't have a hardcore as well. I get that Portal is probably why they would forego HC in the other modes but if they remove or screw up the progression element, my friends and I won't be buying this game.