DJ6,
We went to Shetland in August and there were a few tourists but most probably went by ferry as the flight schedules were still thin. Also, only a few hotels were open and museums and attractions were very restricted if open at all. The season was a bit of a write off particularly as it effectively ends in September. Having said that, the weather was incredibly good and it was a pleasure to see the islands at their best. Had the weather been more traditional it would have made for a dull holiday for all but the toughest nature/walking types as most venues were closed. I can imagine there will be a greater interest this year if we can just get out of these restrictions.
Nice to see Shetland being practical. Taking cash on the ferries was an issue so they just took your name and address and let you on for nothing. I received a modest ferry bill from SIC a couple of months later.