In this ISDC 2015 presentation from Nanoracks, they talked about unmanned space lab/station being on their wish list.
There are a lot of merits to an unmanned space lab, cost being the most important thing. Not all the technology is in place to make this possible just yet but it is getting there.
The Unmanned Space Lab.
A free flying Orbital Cynus is the prime candidate for this.
1) It would need to fitted out with nanoracks.
2) Robotic arms to load, operate and unload experiments.
3) Airlock or/and Docking port to receive robot supply vehicles.
Supply vehicles can be disposable but there is a requirement for returning samples to earth. Intuitive Machines' TRV is one possibility for this. http://spacenews.com/42387commercial-vehicle-promises-more-frequent-return-of-iss-experiments/
Because their are no crew on board, safety requirements can be relaxed. This would allow better propulsion systems on TRV, which will be necessary to enable it to reach Lab after deployment by LV.
Sizing supply vehicles so they can use the up and coming small LVs eg Firefly, LauncherOne, Electron allows for lower cost and more frequent launches. Cost per kg maybe higher than ISS but they don't need to carry crew supplies and station spares, so cost per experiment maybe comparable than ISS.
There are a lot of choices for orbit choices, but being close to ISS has a few positives. The space lab could visit ISS for servicing that only a human can do. Supply vehicles could ride share on ISS supply missions, eg mount TRV in Dragon trunk.