The Tornado and F18 is far from too big, heavy, loads too high for Olympic mixed or all female crew (We are talking about athletic women / men). Both classes both have mixed and all women crews currently racing at both club and International level. There are a lot of female sailors out there who would handle the boats comfortably, not only currently sailing multies but from other classes such as 470s, Lasers, RSX etc. Could see a few cross into Multi sailing.

I would like to see a OD boat such as a Viper as the next Olympic boat but would be just as happy with the Tornado.
Personally I would not like to see an F18 or F16 class chosen. I believe the Viper is far enough outside the F16 rules though and can stand alone as an OD class enough to warrant it for Olympic selection. Boat has similar performance to an F18 however the loads are a little lighter, boat is lighter, 125kg for sloop, several thousand $$$ cheaper. Its ideal crew weight is a little lighter also, somewhere between 120kg to 140kg combined. More suited to mix or all female crew than the F18 is. The Tornado also suited to lower crew weights than the F18. About 140kg being ideal.

I believe the Viper would be an ideal choice for mixed crew for 2016. As more females become involved at an Olympic level, then this could warrant male and female classes for 2020 with the Viper for women and the Tornado (M20 or Narca's new F20) for male.