@Fabiola *********
I got the warning in May, that was my second entry this year, I was told specifically get a visa, an entry was put on my file (IO's words not mine), I cannot specifically say that it was a heads up for these changes. When I spoke to Pathum Thani immigration in early June, the feeling I got was that they were targeting the criminal elements that abused the system. Genuine Travellers would be OK.
I basically got 4-6 months warning, again I've been doing 28 day entries for at least 3 yrs, 4 times per year, no extensions.