Frontier dropped those plans pretty early on, if they ever really existed in any meaningful way.
I suspect the process of dropping them was rather more gradual - they started (and so did their original backers/fans!) very naive about what "Elite but MMO" actually meant for game mechanics, implementation, etc.
They probably started to figure it out sometime around the initial Powerplay "overheads" disaster but by then were pretty much locked in on Horizons, so the first sign they'd actually figured it out was Beyond.
ED could probably be salvaged, though again I truly believe it dose not have that much time left in it's unique position with the likes of star citizen slowly gaining momentum, starfield, and unforeseen IP's snapping at it's heels.
I think it'll last quite a bit longer - sure, there are other games set in space, but none of them are directly competing with Elite Dangerous, and there are good reasons for a new entrant not to try that either.
Broadly I think the requirements for "Elite but better" are that it has to keep the things which distinguish Elite from other space games.
1) Persistent multiplayer
2) Massively oversized game world - and specifically the ability to explore a vast unknown
but not being only or even primarily about exploration
3) Primarily about flying the spaceship in first-person real-time, and related activities
Those are essentially contradictory requirements - dropping any one of the three to focus on the other two would make your task
far easier, still let you make a great "space game", and much reduce the chance that you join the ranks of "space game projects with a promising prototype that were never heard from again". The amount of tech you have to get lined up at the engine/stellar forge-equivalent level to even try to compete with Elite Dangerous - long before anything like "what do you do in the game?" and "is it fun?" gets asked - is ridiculous.
...and why would you want to compete with Elite Dangerous anyway? There have been basically three successful space games released in the last decade (ED, X4, NMS) and maybe a similar number started and painfully dragging themselves towards release. With so much room to do something new and interesting, I know I certainly wouldn't be trying for "ED clone" even if I had the budget and team capable of it.
So in practical terms, most companies
capable of making "a better Elite Dangerous" are also
sensible enough not to try to do it.