I think they have a great opportunity through Portal to increase player engagement while they sort things out with the rest of the game. The foundation is there and they have the ability to create, promote and monitor persistent official modes with all of these assets. ....the server browser, etc.
In all honesty, I think they should prioritize the progression cap problem so that it encourages more people to dive into the mode. Why they can't at least create a cap system for Mastery unlocks, etc. like they do with XP is beyond me. Instead, they just say no progression in that respect which makes no sense. They can limit the kills, etc. awarded to advance in those areas per minute like they do with XP. At the very least people will feel like they are advancing which is better than nothing at all.
