Regarding another, a replacement, operator coming in to operate the routes.
Well Tresco is about to lose ALL air services and with only a 1,188ft grass runway it can only be served by rotary wing but with PZE about to close and St Just owned/operated by Skybus then, and unless Skybus are about to go rotary wing, then the nearest mainland licensed aerodromes are Perranporth, NQY and Bodmin for any rotary wing to operate from/to, additional flying times = higher and non competitive fares.
At least St. Mary's can take fixed wing Twotters/Islanders so perhaps there is opportunity for an alternative fixed wing operator to fill the gap but, again, the nearest mainland licensed aerodromes are as already mentioned, Skybus aren't about to allow a competitor to use their Lands End aerodrome.