As most Star Trek fans will tell you, preserving canon is very important to the core of the Star Trek fans. But there have also been many voices calling for a partial or a full reboot of the Star Trek franchise, partially because of some of the choices that were made by B&B and some indiscretions of the last Enterprise tv series. One such was the reboot in which JMS (of Babylon 5 fame) was involved. AJ Abrams may also be doing a partial reboot for the upcoming movie.
But regardless of what happens to Star Trek in the future, if there is going to be a reboot, I think there is a simple way to do so while preserving canon: We have already established in past Star Trek work things like parallel and alternate universes, temporal and spatial anomalies. To do a clean reboot, the new Star Trek handlers will have to simply pick a spot in Star Trek history and create the split on-screen: Make it clear that the new thread is in a different reality/universe than what has already transpired. This will allow the rebooters to pick and chose on what they preserve from the existing Star Trek and what they can change to their liking. This will also allow the existing Star Trek universe to continue as it is as well.
Having said all that, I am not necessarily advocating a reboot of Star Trek, I am simply providing an idea on how to do the reboot in case a decision is/has/will-be made to do so... What do you all think? :-)