@Nauros
I doubt we can count on it being a one-off. There are new planets yet to come, and new special missions might be added. With each new planet there's at least one required character if not several. I would actually hope that for those planets that require a toon already in Ops during the same phase that CG would act to swap in some new toons.
I don't have any special knowledge or anything, but I would expect this to happen at least once a year, since I think they'll add planets at least once a year.
But also ... let's be serious. The investment in 5B isn't devalued. He's actually a core part of the Reva mission squad and he's required for GI, so you were going to take him to r5 anyway, and most people were going to take him to r7. No one is investing in 5B **only** for Ops missions.
In fact, people have been complaining about the 5B requirement ever since the Reva mission came out. CG is actually doing us a favour.