My in-laws shul in West Boca seems to double whenever I've visited over the last five years.
I think that there are many reasons for this trend.
In the Frum world, I honestly think that cost is the driving factor. Young kids getting married today are priced out of NY/NJ and are looking for a cheaper alternative. They find that the relative cost of living and the balance between it and differences in salary puts them in a better financial position. This is why the frum world is seeing growth in places like South Florida and Houston (among others).
In the world in general, the exodus isn't so much from liberal states, but from high tax states - mostly in the northeast. IINM, NY and CT's growth rate is tiny, compared to Florida's, but also to California's. There has also been movement to other lower tax/no tax states (TN, comes to mind), and I think this trend will get bigger over the next few years as companies will be more likely to close offices and be more open to remote work. (i.e. if I can live in Nashville and work for Amazon or Microsoft, why wouldn't I?). This of course will lead poorly run, and tax heavy states like NY to come up with new taxes, further causing more businesses to leave.
In this year's census, I wouldn't be surprised if NY loses at least 2 congressional seats because of it, by 2030 maybe even more.