Keeping to one game reduces confusion with the franchise
I think good lore and planning in a franchise does more to reduce confusion ... but we didn't enough of that.
Sunk cost fallacy: so much time, dev hours and money has been invested in this game, it might be better to keep going
There is no proof I've ever seen that Frontier ever thought that way.
Elite Dangerous is a known quantity
Yes? That can be both a good and bad thing.
It's easier to keep going than it is to do something new
That's not always the case or philosophy. It's heavily dependent on the facts.
The code for ED is a mess as it has been added to and added to and each time they have to fix things that are caused when they add new code
OP has no proof that the code is a mess unless they've seen it. It is likely that it is in places, but no proof. It's much more likely that Frontier is having a hard time finding enough developers with experience in their IN HOUSE game engine.
Frontier have learned so much since starting ED
Given what I've seen the last few years Frontier has learned a lot in some areas but very little in others. I could populate another five threads on this.
It would be easier to put in things the community wants that would be harder in ED because ED wasn't designed from scratch for things like walking around and ship interiors or fleet carriers etc
In fact, Cmdr Braben said the game was designed from the start for all of those things, but in the end it didn't seem to help. I personally am not sure why ... because I don't work for Frontier.
Frontier are actually losing money with ED because of all the Lifetime Expansion Pass holders who aren't buying expansions like Odyssey. Elite Dangerous 2 would mean a fresh start without an LEP and therefore income from everyone, not just those without the LEP.
The final proof the OP did no research, because this is simply untrue. Frontier has made many millions in ROI from Elite Dangerous and there is no proof LEP made any dent in that profit. It does, however, remain to be seen if this profit will continue in the long term post Odyssey. If the profit of Elite Dangerous doesn't continue, it won't be because of LEP, it will be because the game went in a direction other than where its audience wanted.
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If Frontier does decide to make a new Elite game down the line, they should abandon the use of their in house game engine and/or contract the game out, as
I said in a more cheeky way earlier in this thread.