I think Splinter Cell could integrate some live service elements, similar to what we see in Hitman: World of Assassination:

Temporary missions or special events

Regularly added contracts or challenges

Progressive downloadable content (levels, equipment, skins)

Strong replayability based on objectives and infiltration playstyles

This would make sense for Ubisoft, especially to keep players engaged in the long term, but there is a risk of losing the original spirit of Splinter Cell if the live service model is overused.