You're opening up a huge can of worms here.
Aye, surely. 10 years ago, a survey was done on the 192/8 swamp, and it was estimated that even at that stage, 60% of the registrations were uncontactable. I can't see how thing would have got better in the interim, but does this mean that we officially declare this space lost? Whatever about reclaiming blocks previously assigned, what about blocks assigned in the future? Are we also going to commit right now to losing these blocks if they are unused, or are we going to attempt to fix the issue? I mean, there's a massive problem here. Losing IP space to posterity just because we can't be bothered to put policies in place to deal with the issue is frankly rather unwise.
'Getting back IPs' means contacting peers and upstreams and telling these parties to stop accepting the announcement from the non-paying company. If the company is still paying bills to their upstreams, do you think upstreams will take kindly to this action ? The RIPE NCC deleting the inetnum object doesn't mean the addresses stop routing ...
The RIPE NCC is not the routing police; it's a registration clearing-house. LIR's pay money to guarantee that the address space blocks they are allocated are globally unique. It's up to carriers to ensure that their customers' announcements are legitimate. Anyway, this is getting seriously off topic for 2006-05. Nick