Everybody is waiting for HL3.
I want NOLF3
I could definitely see starting over with a reboot, which would also give the studio involved a chance to dodge all the rights issues by doing a 'spiritual successor' and renaming everything. 25 years later you're likely trying to attract newcomers much more than you are fans of the old games that want specifically more NOLF. I'd also be interested in a cold war era spy thriller that played it straight, real spy history has a lot to pull from that could be weaved into an intriguing story to play through, and NOLF did touch on some of the issues around spying like taking advantage of people.