Possible, especially with politicians and interest groups actively working to keep the American people divided into groups (racial, ethnic, immigrants vs. non-immigrants, LGBTQ, feminists, etc). There has always been a human tendency to band together based upon common history, ethnicity, religion, etc. People want to live and work among those most similar to themselves, sharing a cultural or religious heritage, sharing a language, and so forth.
As far as creating new states, or reforming existing states, that would require Congressional action, probably based upon local or regional referendums creating pressure on congress critters to pander to one group or another.
There has been talk about dividing California into two (or more) states for decades. Similar sentiments exist in Oregon and other places. While the population of a state may be all for the plan there will be nothing accomplished without an act of Congress. Pretty unlikely to happen; who will be responsible for debts & pension obligations, etc, and who will get the assets? The kind of issues that can ignite civil wars.
Mexico, on the other hand, has never really had a functioning national government. The best term to describe government in Mexico is "kleptocracy", which is not that much different than the organized crime cartels. As long as the cartels have the huge cash flows from willing drug purchasers in the US they will be capable of operating as de facto governments within their spheres of influence.