Although Ubisoft did not mention any news about Splinter Cell, in a YouTube Live at E3 video, the CEO of Ubisoft has said "We are not forgetting Splinter Cell". Ubisoft Toronto's Splinter Cell: Blacklist was the last Splinter Cell game from 2013.
"I can't say much about that. For sure, all the Clancy games are taken care of. It's just that we have a lot on our plate at the moment and The Division continues to be played and Rainbow Six too. I think yesterday was even one of the highest numbers of players playing...So all the Clancy games are coming along. We are not forgetting Splinter Cell."
Ubisoft did announce Starlink: Battle for Atlas which will be available in Fall of 2018 for Xbox One, PS4, and Nintendo Switch.