When I originally started looking at all the alternative steem applications the suggestion I made was that the higher witnesses could perform security audits of the new platforms. 

The idea being that witnesses:
(a) Are already in a position of trust
(b) Have more to lose (their witness earnings) than they have to gain by stealing keys
(c) Are typically technical people
(d) Are generally looking for advertising opportunities which the new platforms could provide

I still think it's a useful idea. It probably happens to some extent anyway. It would just be good to have some kind of rating / stamp of approval to guide people that aren't technical (the majority of Steem users).