I'm not prepared to rule it out. I mean, plenty of people were certain that there would be nothing new after the required 1 year of live support, but that has already been announced. We already know more 2042 maps are coming (or anyway, at least one more in season 5). Just because they haven't announced beyond that doesn't mean much -- they usually don't publicly announce plans very far in the future.
Up until pretty recently they've been focused on fixing bugs, adding missing features, and reworking unpolished content -- basically getting the game into the shape it should have been in at launch. To some extent that work is still not done, with the squad management changes and the two remaining map reworks.
Alongside that, they've also had to add new 2042 content for each season -- new specialists, maps, vehicles, and weapons.
Given all of the above, it's not surprising to me that Portal content would be on the back burner. As much as I want it, I acknowledge that they have finite resources, and the above things needed to take priority.
But now they are nearly done with the primary reworks and fixes, and while there will be season 5 and (seemingly) year two content, they've already stated that they're done adding specialists. So they should have more bandwidth to consider things like adding Portal maps.
Given that more people are playing 2042 than ever, and given that the game is finally hitting its stride, they could really invigorate the community with something like this. Plus it would be further evidence that EA/Dice are committed to 2042 despite its rocky start.
I'm not naive or hopelessly optimistic. I realize this may not happen. But I don't think it's unrealistic either. So if it is something they're considering, I want to at least make sure they're aware it is something people want and that it would buy them a lot of community goodwill.