Since you ask...
Obviously I think it's a negative thing, but not entirely surprising - bad ideas from the USA tend to find their way sooner or later, and besides, for most of the history there has not been automatic relegation from the football league. I suspect also that the money lost from no fans at matches forced the matter (and consider, for example, that Arsenal were making as much on one match day (allegedly) ass Sunderland did in their entire season - when they were in the Premier League). People who asked for these restrictions must understand that there will inevitably consequences, and I suspect (though have no way of knowing) that this was one of them. Of course, when the fourth division was a closed shop, crowds received a significant boost with the introduction of playoffs and automatic relegation, with the clubs that have come in getting more fans than the weaker football league clubs used to get. It won't necessarily be as bad with this proposed closed shop, but it may get a bit stale after a while.
As for what should be done, I'm not sure that the authorities should get involved. For safety issues such as after Hillsborough, yes, but what possible basis is there for them to tell businesses how to run their affairs? they don't have relegation from the Highland League either. As for the FA etc. banning them from competitions, I suspect they won't be that bothered about being banned from the League Cup or not being allowed to give up their players for international matches, and will further believe (probably correctly) that an ESL is a superior product to the PL (I mean Bournemouth? Come on!). It is hard to see an alternative other than trying to persuade them to amend or abandon their plans by making them a better offer - which could be what this was about anyway, despite their protestations.
In any case this has been a long time in the making. There was a manager sacked from Spurs late 70's early 80's who despaired over the lack of loyalty shown by the club compared to what would have been expected in the past and when returning to White Hart Lane (as I remember it), quipped "there used to be a football club there". And in 1986, we only got automatic promotion to the fl to try and pacify the big clubs and see off a threat of some sort of breakaway.
From a non-league angle, the interesting question is, will all those United fans tearing up their season tickets (if indeed it is a significant number) consider watching clubs such as FC United and other non-league clubs?