The measures apply now...it is the income level that is changing.
It is a relatively small part of legal immigration that is being addressed..the numbers are small. It does not address any illegal immigration issues. Apart from making some spouses illegal in the future.
It does however affect some UK citizens who live in Thailand and may already have a Thai spouse and although married for many years, if they haven't applied yet to give their spouse residency will from the spring, find they have to jump a much higher hurdle.