No big change will have a completely positive outcome, but many of those people could move to working with sustainable options. The only bad thing i could see is that some professionals in that category pretty much wasted their time.
ok, let's say hypothetically, every person who had a job in oil, coal, etc. industries was able to move directly to the kind of work you're talking about. then there would be no change in employment. so... bad argument
now let's say every person in the problem-industries lost their job, period. and a bunch of jobless people got jobs in the good stuff. then there's technically no change, except you've got a bunch of people who were accustomed to having money being jobless, even if some people who were used to unemployment gained jobs. so, again... bad argument