Wizzair's London bases are Luton and Gatwick. Unless there is approval for a new terminal, Luton is approaching its capacity - an increase in pax allowed from 18m per year to 19m is not going to make a huge difference if flights are being upgauged from A319 to A320 and A320 to A321. Gatwick isn't exactly empty either - I'm sure Wizzair can get hold of a few slots here and there, but thinking strategically rather than tactically, this isn't going to provide huge amounts of airport capacity quickly. I know they have an issue around inspection of aircraft engines... but this should be largely resolved by late 2024.
Should Wizzair look elsewhere in and around London for future airport capacity ? Neither Heathrow nor City are suitable for Wizzair. I don't see any of Birmingham, East Midlands, Lydd, Norwich or Southampton being useful to Wizzair for taking pax to/from London. Should Wizzair look at Southend ? Or even venture into the enemy's lair at Stansted ? Or should Wizzair just deploy extra capacity to routes that don't touch London and its suburbs ?