Not only has The Flash boss not ruled out returns for Tom Cavanagh and Carlos Valdes, but his comment that the show is “happily keeping the door open for return appearances” indicates that the Season 7 finale won’t be killing off Cisco, and at least one version of Wells must be out there somewhere, unless flashbacks or visions would be necessary for a return.
It’s also worth noting that Cavanagh will appear as a guest star in future episodes of Season 7, so fans haven’t seen the last of him regardless of what happens in Season 8.