Fake async rep target

How easy would it be to implement a fake async rep target?

Perhaps even as something that a server could allow a connection to 
request?  (ie a suitably permissioned connection could convert itself to 
receive n async replication stream, rather than being statically 
configured?)

I know that it sounds a bit bonkers, but a while back I worked on a 
system where we configured a rep target (using OpenServer) we could 
observe changes to tables and enqueue secondary processing. Rather 
painful in that case because of the way that repserver is configured,
and I'm not sure it was worth the pain when configuring test and dev 
environments.

However, in principle, it seems that this is quite an elegant standing 
for a whole raft of trigger functions - and probably a lot cheaper to 
execute. The key, I think, is to be able to allow dynamic attachment of 
such a 'change feed' by an account that has god-like read access.

Is the existing async rep code amenable to this sort of abuse?