Dominant Parties in a given area tend to beget their own demise over time. Whether this be through alienation of the out groups that aren't part of the power dynamic, but grow over time to overthrow said power group, or the alienation of a previous component of said power dynamic that thus causes them to drift to the other side.
I don't think any map alignment or regional differential in the EC map is permanent long term.
To some extent, you can see this at the state level, where governors from the majority party go too far and the backlash causes voters to elect someone from the minority party. Larry Hogan and Laura Kelly got elected in part because voters Maryland Democrats and Kansas Republicans went too far and needed to be kept in check.
In general, one-party dominance is unhealthy for a state's political culture. It breeds corruption, causes inertia and allows extreme candidates to get elected. Republicans should be able to compete in New York, and Democrats should be able to compete in Oklahoma, let alone Ohio (seriously, how are Democrats there so weak at the state level? It's been a presidential swing state for a century).
