Grammar is really just an agreement between all of the people who use that language. Lauren Gawne, Australian linguist, on the podcast "Lingthusiam" with Gretchen McCulloh, Canadian lingusit and author of Because Internet: Understanding How Language is Changing. (Which looks like great fun and I have put it on inter-library loan request.)
We think of grammar as something a bit holier than that if we were raised in previous generations, but that has always been the truth. Grammar rules got put in place by oh, just anyone who felt like it and some of them caught on, in parallel to the middle class arising in England. The elites wanted to maintain their superiority by speaking properly, but as with any regulation, one can game the system immediately and the rising classes bought books to learn how to imitate them.
But do not despair. If something is an agreement between us all you can go as slowly as you like adopting the new ways. I do recommend you understand the nuances of changes as they happen, but you don't have to use them yourself.
John McWhorter recommended the podcast in connection with his interview of McCulloch and I have listened to an episode and put the whole series on my list. I learned that aliens apparently speak in Object-Subject-Verb order, as this is both Yoda-speak and Klingon. It is the least usual order among Earthlings, who usually speak languages with Subject-Object-Verb or Subject-Verb-Object. Gretchen speaks too quickly (like I should talk), but I adjusted to that and recommend it.