I think that there could be, but it won't ever be canonized. The clans were special in some respects but equally, before the Ameris coup, rich men could and did muster fleets of hundreds (or more) of jumpships and in at leat a few cases decided to found their own personal kingdoms. It's not at all unlikely that a few were smarter and were successful. Heck, we know it can be done, a'la the Tauran concordat which held off the SLDF with a fleet that was superior to most of hte actual house lords. They lost, but they were certainly a "major power."
So why won't we ever see them?
1. Distance. The Clans invaded for ideological, not pratical reasons and there's nothing the IS has that an advanced society couldn't make for itself. Sure, you may get the guy who wants genuine Tharkad snow globes, but he's not going to travel 1500 LY to get it. He may, at most mention he wants it to a trader who tells another trader, and 10 years later, some guy hears that thee's someone interested in this and started the process reversed, selling snow globes to at rader who is heading in that direction etc.
In other words, most practical contact would be much like Rome and China-- very indirect and with nobody really all that concerned bout who is on the other end.
2. Practical matters. We have yet to have a sourcebook on the Tortuga pirates, Fitvelt groups, etc, etc, etc. We have yet to have any single time period so completely covered that people don't want anymore books. But if you add another major deep periphery group you have to have likely at the minimum a "house book" talking about them and thier enemies, a tech readout, some adventures, etc, etc, etc. Some peopel will love it, but the ones who have been waiting for their IS sourcebook forever will neither like it, nor honestly have much use for it.
3. Foreclosing creativity. This is a big one for me. The more you talk about these regions the harder it is for players to fit in their own creations. If we find out that beyond the OA there is a nation the size of the Draconis combine, it might make things ab it hard if you want to put your own people there. By not movnig out of the IS and near periphery, the writers give us, the players more of a free range for our own work.