Get rid of all of them except .com. Just don't issue any others, and leave the ones already there until attrition destroys them.
There's no actual value to having different tlds for the website xxxxxx, other than to make money for domain sellers, who frighten the owner ( renter ) of xxxxxx.com into buying more domains for the same site to stop competitors from using xxxxxx.net or xxxxxx.org. I have never come across a real site whose domain name led to an entirely unrelated site run by different owners based on the .yyy.
Should one imagine this would lead to not enough site names, there are enough words to be combined in any language and enough languages to accommodate millions of sites. Plus losing the fake/crap sites ---scraper-sites for just one instance --- would not harm the internet at all.