I gather you won't be paying more for core improvements. My guess is more paid content will be for straight up new features.
If I had to hazard a guess as to how Frontier will monetize the game from here on without "season passes", I'd wager they will be utilizing the Elite Store to charge for certain things other than just cosmetic DLC. They already have the Store in place and it integrates very well with the game, so why not take advantage of that? For example, all of these core and QoL improvements will probably be free updates for everyone to prevent fragmenting the playerbase. However you might start having to pay in the Store for things like:
- Volcanic Planet Landing Permit (new planet type to land on)
- Gas Giant Flight Permit (allows flying into GG atmospheres)
- SRV MkII License (new SRV)
- Panther Clipper License (new ship)
- Imperial Explorer License (new ship)
Ideally these would not be expensive to buy, say $5 or less for each, but over the course of a year or two you might end up paying the same total amount that you would have for a season pass like we did for Horizons. The big difference now being that you can pick and choose what features you want to buy and which ones you don't need at all.
That's my gut feeling for how they'll be handling this going forward. Totally theorizing here though.