I don't understand the significance of HL:A's ending...

It essentially leaves you exactly where you left off in Episode 2 but with some roles swapped around. It's still just as unresolved as before, and the plot about the Combine is the exact same. Alyx and Eli essentially swap places where before Eli died and Alyx had to grieve but continue with Gordon into a tastefully fatalistic finale of some kind, and now instead Alyx is missing due to a G-man deal, and Eli just survives, leaving him to I guess... say "take care!" to Gordon who goes on to look for Borealis anyway?

I feel like the tone of the ending is trying to be so "Look, we subverted everything!" but all I got was "Look, it's still Episode 2 except Alyx is gone except you're still totally gonna play Gordon in the next game!"

I suppose the potential the ending leaves you with is to break away from anything Half Life 2 related in a new game, and just make a clean-slate Alyx game in a world that is every bit as shocking and foreign as City 17 was to a Half Life 1 player. But if the intent was to do something to the HL2 canon in bringing it new hope for an Episode 3 or Half Life 3 as a follow-up to the Episodes and Alyx, then I don't understand what the point was in reviving Eli. He already gave you a plot to find Borealis and his death is only relevant to Alyx's emotional journey, which is now reverted for seemingly no reason than to imply that "something has been changed."

The kind of subversive "fixing" of Half Life's eternal stasis as a franchise is something I feel the ending is implying but I don't really feel it.