Dooooom!
Seriously though, I think you're wrong because, ironically, of the Steamcharts. They showed that a LOT of people really want to play ED, but aren't currently doing so - peak player count up by a factor of 4-5x. There's definitely a market for ED expansions and if FDev can do a better job of tapping into that (and not release a steaming pile of garbage next time) then there's still money to be made. The fact that they're still adding content to ED and EDO shows they haven't given up hope yet of turning things around. If EDO was to be the last expansion, they'd already have binned the console release - otherwise it's just a waste of effort.
I don't think people should underestimate how much it means to Our Lord and Saviour Brebus. It is his baby, and what put him on the map. The other side of things is that a "complete reboot" would bin off the kickstarters and LEP owners - and they're at a point now where they wouldn't need to kickstart it, instead just release it as a new game ("We told you we'd give you everything for the lifetime of Elite Dangerous, that life is now over, soz") so more monies coming in.
And honestly, I'd be alright with the toxicity of the current release disappearing into mists of time with a reboot of sorts, and I say that as a beta backer with an LEP. A new game, new engine, picking up from where this left off, designed and built with non-potato hardware in mind, with all the features the various focused feedback threads have been asking about, and shag it toss in the oul' ship interiors and other bits.
(For the record, I genuinely don't believe this is actually in the works at the minute. But I wouldn't write them off changing tack to this sort of direction at some point... maybe even offering it out to another studio to develop under the Foundry)