Original MW for PC lasted, well, forever. A good following of people anyway, enough to the point that they worked to find a workaround for when Punkbuster gave up support for it. The Remaster will definitely bring out a good number of people that had given up on CoD a long time ago, myself being one of them. Couple things I could see them doing that could kill the following; 1. No mod support 2. No actual competitive scene foundation.
The eSports scene could easily see be the saving factor if the game kind of got stale and took a dive. A competitive ranking system would definitely drive up the player count. Think ESEA from CSGO. *IMO. The next few months are definitely going to be positive though.