Thanks Leon
If you are already a PR, you are already a PR. They can't change the rules retroactively. The 38 occupations are only valid for skilled worker applications made since February 27 this year, the day they announced they were changing the rules.
The only way you can lose your PR once you have it is if you commit a crime serious enough to warrant that, if you are found out as having lied to immigration to get your PR or if you have not fulfilled the residency requirements of living in Canada total 730 days or more in any 5 year period.