Halo is already doing this, and the season passes are free. I've paid for every single season pass up until now, yet only recently have I had the time to grind out 100 levels. It'd be a huge quality of life improvement if we could progress in previous seasons while we wait for Witch-Queen. I'm already over level 100 this season, so I'm kind of running out of stuff to do. Plus I already purchased those seasons, so I should be able to progress through them and claim what I purchased at any time. It would be easy good press. You could even sell the previous seasons at a discounted price as an incentive for players to keep playing. I know it isn't likely that anything will come of this request, but I'm already kicking myself because I missed out on those seasons because I didn't have time to play. If I don't say something, nothing will change.