No. As long as there is progression there is progression. End-game is when the game can be "won". Elite Dangerous cannot be won or finished. People may get a feeling of having completed or accomplished what they wanted to do or perceived is what they can do within the game. But it is different for everybody, and as already pointed out elsewhere numerous times, we have 400,000,000,000 stars to visit.
The only way the game is a mile wide and an inch deep is in the shape of the galaxy, which is roughly 130,000 ly wide and maybe 1,000 ly thick on average. If for some reason you cannot find enough to do within the vast scope and detail of this game board, it may simply be that you have exhausted what you are willing to do for now. Others will find stuff to do though, which only reflects the different take people have on having fun within this game.
Credits and credit earning rates are aspects of progression, but open ended just like the game itself. The progression to ever more costly ship types is progression, and the ranking with super powers and different factions are progression as well. Neither really lead anywhere though, and we don't get more involved or demanding game play aspects from going through these. Perhaps fleet carriers could have been an end game asset, but they are not game play in themselves - FD largely wasted that opportunity by making them largely similar to other ships bar some clunky interface and interaction aspects.
So in short, no, progression does not imply end game. Only if you are stuck in an MMORPG mindset. If you are, you don't really understand ED.
Mile wide and inch deep.
Yes we do have 400b star systems to visit. but how many offer us ACTUAL content?
Another non-landable planet is not content.
A single star? 399,999,999,999 more to go with hopes for something more.
130000 LY apart. How much of this is covered in content? Vast space is not content.
Even if you'd make it 500,000 wide with nothing inbetween, it wouldn't make any difference. Because the void is... well... dead space!
So i'm not stuck on a number of how many billion systems we are offered to explore or how wide and tall the galaxy is.
I'm more interested in how many of those numbers offer something to us!
Here is a good analogy for you:
You come to a book store, and you are looking for a good read. Something to entertain you.
I give you a book, it has 50 pages of a interesting story.
Now I give you another book, which has 100 pages, but every 2nd page is blank. "Blaze your own trail/write your own story".
Now I give you a book with 200 pages, which starts with "Chapter 1" on page 1, and "The End" on page 200.
Which book do you find the most engaging or interesting or entertaining?
So really, it doesn't matter how big you make the galaxy, if you don't fill it with anything, it might as well not be there.
Similar to the Australian Nullarbor. You have a 200,000 km2 of NOTHING! But it's so big! yet it's void!