While I appreciated that the game let me know when I'd be going into the final battle, I also knew I had plenty of places yet to "discover" in the available NV landscape, plus DLCs, so I knew my fun wouldn't stop with the conclusion of the main quest. I had a handful of previous saves as I entered Legate's camp, but the dang soldiers were pretty tough on me, so I wound up saving over almost all my previous saves at various points, just to make sure I'd have opportunities to change tactics without starting the final battle over again. (And yes, NOW I remember that Fallout 3 also required a previous save to continue playing, but that wasn't in my mind during my final New Vegas battle...)
At any rate, I ended New Vegas with only 2 previous saves: 1 from about 2 hours in, & another from about 9 hours in. After 70 hours of gameplay.
Post-credits, I quickly realized I couldn't continue playing. So I immediately downloaded "Dead Money," remembering that the DLCs from Fallout 3 enabled ongoing play. But then I learned you can only access "Dead Money" in-game (not from a menu screen), & not during the final battle. But all I HAVE is my final battle... except for my save 9 hours in. So I tried loading that old save (super depressing), but apparently you need to be at least Level 20 to even receive the "Dead Money" radio signal -- so I'd need to invest DOZENS of hours before I can even reach the in-game signal to begin the DLC. I’ve played another couple hours already, but no signal yet.
Dear Bethesda: If you're going to explicitly warn players the final battle is about to begin, PLEASE PLEASE explicitly tell us to preserve a saved game for ongoing play. Better yet, create a set-aside saved game for the player (e.g., "Return to pre-battle save? Click here.") Or, even better yet, allow the DLCs to be accessed via menu (with earned XP intact), like "Red Dead: Dead Nightmare" and lots of other DLCs. Seems like menu access to DLCs is something you could STILL add to the NV package -- please consider it!!
True, lots of people are more in the loop than me & probably have more saves and/or aren't saving over previous saves like I did -- but the fact is that no one told me NOT to. I'm really good at following basic instructions when I receive them, I swear.

I'm just bummed because I love the game so much & would love to spend gobs of money on NV DLCs. But as it stands, if I have to basically start over again, I'm looking forward to spending my money with a different company.