TSID 104 has gone from the regionals. From the old national HD and SD overflow transport streams, 36-41, 43 & 44 have been decommissioned, similarly 42 & 45 have been decommissioned but have been left in the NIT. The frequencies for those have been redeployed but could be clawed back if needed. Although any other services, such as DOCSIS, now using the frequencies would have to be rolled back. VM's plans for DOCSIS 3.1 aren't really in the public domain, so guessing at future spectrum allocation isn't really helpful.
Of the original SD transport streams, TSID 12 has been cleared and is mothballed other than the occasional Channel Update slate, TSID 13 has been redeployed to HD, TSID 14 has been redeployed to BT Sport 4K and adhocs, TSIDs 15-19 have been cleared of services and mothballed.
The next step will, possibly, be repopulating and reallocating TSIDs 12-19 to restore the number sequence and maybe clearing out services from the higher numbered national transport streams and either mothballing or decommissioning them.
Mothballed transport streams can be brought back fairly quickly and whatever is happening to TSID 19 may give an indication of what will happen next. The decommissioned transport streams no longer have frequencies allocated, so bringing any of those back would depend on VM's other needs.