What's happening is a bunch of people are getting involved in semantic discussions as to whether there's a hard & fast definition of "reboot" when it comes to fictional properties. It's a piece of terminology that's been adapted for that use without ever being strictly defined. It was slang, essentially - chosen almost specifically to somewhat avoid the negative implications of the term "remake," - implications that now "reboot" also owns, hence the dancing around the term that the Marvel editors are doing whether they have to do that dancing or not.
But parsing the words they've specifically chosen to use in the press event, and the interviews spinning out of that press event, it's pretty obvious that Marvel has decided this version of "Secret Wars" is going to be their run at attempting/reinterpreting the New 52 plan, but with the years of hindsight that doing it now provides. They can look at what worked, what didn't, and keep those things in mind when they make their own decisions.
The question seems to be whether or not you consider the New 52 a "reboot" or not. And if you do - then that's what's happening here with Marvel and Secret Wars. If you don't - then the Marvel Universe isn't rebooting.
But it's hard to argue that what's happening here isn't the same general plan DC tried to enact with Flashpoint/New 52. They're just hoping/planning on doing it BETTER, thus gaining themselves the same sort of sales-spike DC got, but hopefully maintaining it much longer, and without the dissatisfaction that quickly followed DC's misguided/mishandled attempt.
