NASA, conscious that ISS potentially only has 8 years of useful life left in it, is making the very smart move of helping to accelerate the age of commercial space stations in LEO.
This is a comprehensive article, but the long & short of it is that NASA has put out an RFI for nascent commercial space station operators to berth a full-sized module at the port currently occupied by the +Bigelow Aerospace BEAM experimental module.
This will be a valuable bridging and learning experience for the winning bid, as they will have to build and launch an actual space station module, but NASA will feed & water it once it's attached to the station.
I'll watch this space with interest in the coming years.