Remote administration for infact the whole network, it can be any server like web server,DNS,DHCP, FTP, Mail server. Infact the purpose of this Telnet/SSH server would provide an interface to the system administrator to the configuration interface of these servers and even some network equipment like a switch or a router's IOS.
I don't see the need for a go between for devices that use telnet/ssh for administration. I do see a use for a radius/tacacs type solutioin to authenticate your administrators. As we know, there's nothing secure about Telnet, since everything is in the clear. You may want to rethink what you are doing here and deal with administration on a case by case basis. I can see where you may require SSH over telnet, if the device supports it. As powerful as computers have become now, I don't see a need for a go between box as you describe. I think you will find this out as you go along.