The most important thing is to make windsurfing as accessible as possible, which to me means having the smallest number of boards and sails, with the widest wind range possible.
In the past, the rule of thumb is that boards should be about 13cm appart (eg 85cm, 72cm and 59cm) If designers can extend that range to 17cm, so that you have a 92cm, 75cm and 58cm, that covers all winds from 10kts to 45kts then that would be a massive benefit to the windsurfing world
Let's consider conditions in the UK this summer, glorious sunshine, nice and hot, winds around 10 to 12kts at best. There is often not enough for me to use my Is137, but I may be able to get going on a 90+cm board. However, I want to use my big board with my 8.6 as well (which is crossover size with my 75cm board) - so can clever board designers create a 92cm board, which will work well in gusty 12 to 16 kts with an 8.6 and be as competetive as one of today's 85cm boards?
Also worth considering high wind boards. At Weymouth Slalom in May, the winds reached 45kts. I sailed both my Is101 and Is87 - only in the very extreme races, when I was totally overpowered on my 5.7 was the Is87 the best board, by the time I was on a 6.4, I was quicker round the course on the Is101. So my point here is that at the small end of the scale, a 60cm wide 90 - 95L board is probably the smallest you need for 95% of races