Soldat looks and plays like a 10 year old game, meaning its going to continue to be a niche game in the time of matchmaking, decent anti-cheat, built in voice, account systems, etc. Nothing prevents Soldat from being updated to support this, but it requires a team of dedicated (read: paid) developers to get there, and that's not going to happen.
The gameplay of Soldat will undoubtedly live on though. I'm working off and on on a clone and I'm sure others are. It will be interesting to see if we get another game worthy of being Soldat's successor.