Sadly, I am not sure how viable Sandown is.
I would guess that there are not a great many pilots that own aircraft on the I of W. Certainly even in the "good old days" there did not seem to be many aircraft parked at Sandown, or for that matter Bembridge, and things have got worse since then.
This has left both airfields reliant on other income. Bembridge are fortunate in having a hard runway which is sufficient to cream off any commercial activity (the coast guard flights etc). Moreover having a commercial operator based on the field brings other business and doubtless contributes significantly to the bills.
Sadly, Sandown has very little of any of this and I suspect is almost totally reliant on visitors of which there are just not enough these days made worse but the problems using Sandown when the ground is wet.
In France of course the airfield would be subsidised by the local community - but we are not France and everything must make a profit and a return on the inverstment if it is to survive in modern day Britain.
I shall never the less be very sad to see Sandown lost to GA if that happens and wish them well operating with lower overheads if that proves possible.