LTNman
My 'guess', and that's all it can be at this very early stage of the pandemic, is that by the end of March nearly all international passenger flying will have ceased at all UK airports and that internal flights will greatly decrease in number. Looking at SEN that means that passenger numbers will be insignificant by that time and that will continue for at least six months. Maybe freight flights will remain an essential element of trade with on-line purchasing in particular surging. Even if the pandemic is over by then there will be continued low activity levels until a Covid-19 vaccine is available to everyone. That may take another six months. On the assumption (or should I say in the hope) that the European economy has not collapsed into a massive recession, after that for summer 2021 I think there will be a large pent up demand from those millions of people whose holidays have been lost this year, plus business traffic could return to its previous levels. I don't see a reluctance to travel at that stage, much in the same way that the failure of major airlines in the past couple of years has not resulted in a lack of confidence to make forward bookings.
Where will SEN stand in that scenario? I haven't a clue as nobody can know which airlines will have survived and in what condition they will be. Maybe governments will see the airlines as being essential elements in the recovery and effectively fund the securing of those entities for 12 months; effectively 'nationalising' them as they may have to do with the railways. Without a viable transport infrastructure in place economic recovery will be significantly delayed.
I'm only writing the above because you asked the question, but it's all speculation and guesswork with no firm data to base it upon. I was thinking the other day 'what if I were not retired but asked to advise airports on actions to take at this time?'. The answer to that thought was simple: 'thank goodness I'm retired.'