Get a game that means something to you. If it's not a game of a franchise maybe a game by the same developer.
I'm at 999 games right now. I wanted my 1000th to be Mighty No. 9, because Mega Man 3 for the NES is not only one of my favourite games of all time, it was also the first game I ever bought myself as a kid. So I thought it would be fitting to get Mighty No. 9, coming full circle so to say. Now that it's been delayed (again) I thought about Street Fighter V being my 1000. Since Street Fighter 2 was the first game I bought for my SNES and it sparked my love for fighting games.
So maybe go that route if you have games that fit that formula.
But I have to say, I really like the suggestion to get a new system and make the pack-in game your 2000.
Maybe i should finally get a Neo Geo with SamSho II or KOF94 or a Saturn with Cyberbots
