Most of the time star trek delved into time travel, it was to correct history and keep the future/present the same. But the new Star Trek movies starring Chris Pine had history altered, and this means everything we used to know about the original series may very well be completely different. It is accepted that there are multiple alternate universes, but does this mean there can't ever be TRUE CANON in star trek? Edit: I'm not wondering how the new star trek fits in with the original, certain it shouldn't. I'm asking if there is a canon, or if there is any point of one in star trek
There are indeed multiple alternative universes, but they exist simultaneously in the same multiverse and don't contradict one another (at least any worse than events contradict each other from within any single timeline).
There is one true Star Trek canon, and it contains (at least) 2 copies of Captain Kirk's 5-year mission aboard the Enterprise. Both timelines are 100% canon, and are a part of the same canon. Indeed, there are a lot of alternative timelines in Star Trek that are considered canon.
This is relevant because the timelines can interact with each other so it makes sense for canon to encompass the multiverse.
If we accept that the multiverse exists, whether it be in our reality or in the Trek verse, we must accept that there are infinite permutations for each universe. Having said that, permutations that have appeared in various VALID incarnations of Star Trek are considered canon and other hypothetical timelines are just that and not canon. Other unscrupulous j.j.abrams-esque mock treks are simply unfortunate features of a particular timeline(s) of our own multiverse and are not especially linked to actual Star Trek canon. There might be other realities with other Star Trek canons but they are not relevant to us.