Accept: Nomatter what changes are made, things can always be restored to the way they were. The changes in the timelines in Star Trek in the past were done on purpose to liven things up, If the writers wanted everything to be exactly the way they were, there's nothing to stop them writing a way for it to happen.
Accept: Even if the timeline is changed, it doesn't mean that future events nolonger happen. Timelines are like railroad tracks running beside each other, a train can move from one to the other but that doesn't mean unused tracks cease to exist. They are always there and always will be. The characters in the show won't remember being in a different timeline, but we do.
Accept: Star Trek has been in a decline for a long time now. 40 years of writing stories which span hundreds of years has made it nearly impossible for new original ideas to fit into the timeline without conflicting with already known events.
Screwing with the timeline with the option of returning it to normal anytime the writers choose to might not be such a bad idea. All the events we know still happen, the characters just have no memory of it, and it opens up hundreds of years worth of new ideas with no rules as what is or is not allowed.
Blow up a few planets, make a few species extinct, have the tribbles conquer the Klingon homeworld, it can all be undone in the end and in the meantime we get to see all the characters we grew up loving in a brand new world where anything can happen. Why shouldn't we be able to some things because some writer 40 years ago decided we couldn't?
I have no idea what changes if any are going to be made by this movie but as far as I am concerned the more the better. It will bring new fans to the show, show us things we could only dream about happening but never able to see, and can all be undone in the end.
Think of the movie as one of those great episodes where a character loses their memory, has no idea who they are, and live a different life than what we're used to seeing. Gives you great perspective on what could have been and in the end they remember who they are, everything returns to normal for them but we get to see something we could only have dreamed of.
Now imagine that that character is the Star Trek universe itself.
Not Accept: Nothing.
Sorry if a lot of this has already been said but I was too lazy to read 18 pages of posts since I've only recently returned to the forum.