It would be no different than a logi ship: logi ships are completely and totally useless without others to support. In terms of being useful outside of mining, they’re not terrible transports as non-freighters when it comes to assembled ships (which none of the freighters can carry, save for the Bowhead), ore, and misc goods in the fleet hangar. I generally agree with your sentiment that all ships should be usable solo, but I believe this is a unique situation where, by its nature, an exception applies.
I’m not saying “Orca mining” is a problem per se, but I think the fact that it is a trend suggests that barges aren’t attractive enough to be used instead of Orcas - that suggests there is a balancing issue (not merely an AFK issue). When an Orca can be aggressively fitted rig-wise for solo mining and have an mining yield comparable to a low end barge (esp relative to hold size), you’re having a ship that wasn’t intended as a mining vessel be used instead of a proper mining ship - that suggests a balance issue. In particular, Orcas are taking the place of Retrievers and Mackinaws (and to a lesser extent Procurers and Skiffs), which I consider to be a problem. With fixed, unmodifiable mining bonuses (ie. no more mining rigs), barges will be substantially better than mining command ships, and mining command ships will be delegated to supporting mining fleets (via both boosts and the usual mothership support capabilities) and freight.
Were this rebalancing to happen where, among other things, the mining rigs are removed, then the existing fitted rigs, unfitted rigs, and rigs being manufactured would probably be grandfathered in and continue to exist, but they wouldn’t be able to be produced anymore.
I consider the above changes to be solving two problems at once. As I’ve said, I find the “Orca mining” meta to be indicative of balance issues: if barges aren’t sexy enough to be used instead of mining-rigged Orcas, we have a balance issue. Rebalance the mining command ships, and we solve two problems at once.
This can be reduced even further, which I think would be a great thing for both the Orca and the Rorqual. The Orca’s yield in particular should not compare to a barge.