I think you are right. If the Viper were selected all the other F16's would soon wither on the vine just as the other B Classes did when the Tornado was selected. Devon
The Viper is a cracking good boat and has demonstrated it can carry a range of weights and retain its speed and performance, it does tick a lot of boxes and also is modestly priced compared to say the new F20C, that it has to be a contender if we can get a mixed class in multihulls ( about the only way in my opinion ).
Will it hurt the F16 class, it is sufficiently outside of the F16 rules that it will make its own SMOD class and the more experimental sailors or the solo sailor will continue to develop the F16 class until the Viper starts to fall back a little as the Viper design cannot be updated if selected.
The F16 boat designs at the moment are sufficiently equal in speed in dual handed mode that my guess that both Viper and F16 boats will continue to race together to build numbers on the start line and also help clubs gather big enough fleets to put on top class events. Perhaps in the long term then we may see the Viper go SMOD events as per Hobie has done, if numbers build enough for AHPC to splash the cash on event sponsorship.