There's nothing that I know of in the pipeline but then I don't have all the contacts I used to have. There are local reports that EZY are being strongly courted to return but you would expect that to be the case. One wonders just how much passenger business would have to be booked for S2022 to make it cost effective to re-open the terminal - I doubt if, say, a few times weekly JER would tip the balance.
As has been said above LON just doesn't need SEN immediately post-Covid so a lot will depend on how the various markets recover to make it attractive again to their previous airline customers. There could always be a few surprises of course that bring SEN out of mothballs but that feels like hope triumphing over expectation at the moment.