Sorry I cannot see for one minute that TUI will base one of their 737-800's at SOU.
Not gonna happen, nor is Jet2 or FR IMO.
I may go to one of the open days next month to ascertain their views on the Boeing ever going into SOU, but I reckon the 738/73MAX is the wrong fit for SOU.
They (TUI) have bases at BOH and EXT with a single a/c, but increasingly their holidays in our region from SOU, BOH and EXT are being placed on 3rd party overseas carriers such as Freebird, Albastar, Volotea, Evelop and Air Europa, or using W patterns.
Flybe are dedicated to the Q400 but, from 78 to 90 seats? blimey that will be tight - what about their
business passenger model & that top fare market ?
There is not
AFAIK an upgrade available to existing a/c, but is a brand new HGW variant of the Q400, thus a Flybe order roll-over for new models would be required. (expensive)
EZY I can def see them expanding at SOU once they know the airport can handle it....
BA/CF have recently developed more EMB jet leisure routes (many seasonal) from STN BHX and BRS plus the expansion of their fleet for their latest LCY routes for S19.
They publicly haven't commented on using SOU
AFAIK - personally I think they could do well out of SOU - they have the right a/c and the marketing power and would give Flybe a run for their money, plus any downtime could see getting IT charter work as they have done rather well for some years out of the provinces and Scotland.