If it's suddenly announced next month for release by next summer, we'll know, otherwise there's simply no solid information to base a conclusion on. Paradox won't start building the house until the foundation is poured, so we have no clue whether anything at all has been done toward it, or whether it's already half-done and simply not open for discussion or acknowledgment by Paradox employees. As petertju pointed out, Johan mentioned not yet having a premise for the game, so the underlying foundation may not exist, particularly if the DLCs are already utilizing whatever time and effort can be spared from whatever is up for release in the near future. There is also the real-time vs turn-based choice. Civ 5 is more about building up your cities. Much focus is on outmaneuvering your opponent diplomatically and strategically.

If the preliminary framework hasn't been laid out yet, then there's no point in assigning anyone to do things which may not even be needed, depending on the direction that the project takes. EU 4 is mostly a game of colonization and conquest, peace time is quite boring, especially if youre not colonizing or trade-focused. My suspicion is that IF EU5 is being worked on at all yet, that it's only getting occasional attention from people not needed at the moment for whatever is currently 'hot'. When a few people have no specific duties for their specialty in the current projects, they may get shuffled around to work on a 'back burner' project which won't see the light of day for a couple more years at the earliest. While game companies often have several projects in the works at once, most of the work will be channeled into one or two priority titles.

Europa universalis 5 maori