wdymean "No" it definitely will still be on your library. Valve will shut down CSGO official servers at best, but you can still freely access the game and play on the community server if that's your thing.
Imo even community servers will not be allowed, since faceit will be able to continue hosting servers. Another case of fragmenting player base. That and valve will again have the headache of 128tick in csgo vs 64tick in cs2
The game has the same appID as CSGO. As soon as it releases, CSGO will be replaced by CS2.
At best you'll be able to play the old CSGO by checking the Beta options, but with no dedicated or community servers. It's over.
I mean its not quite in library since cs2 is an update for csgo, but it always has been possible to go back to older versions, and even easier to just download the demoviewer assuming its just the last version of csgo.