It will be very difficult to insure, you're right. Some owners may just not insure it and accept the risk, but I think most will insure it for a year or two (at very high prices) and then stop.
By the way, Robinsons do not require the full 12-year overhaul if they're not flown commercially and are well under 2200 hours by then (most private owners would have 1200 hours or less). You have to replace some calendar components then, and do an inspection, but not the whole overhaul. It's still expensive of course, but I think it's 1/3 the price of the overhaul...?