Originally posted by Spodeworld and that probably will even make it more difficult to rebrand lenses.
You are probably referring to Pentax lenses which are rebranded 3rd parties, e.g. Tamrons? Yes, that lens supply source is dried up for ever for Pentax.
However, e.g. Tamron is/was known to make exclusive lenses for camera makers. Probably, Tamron and Tokina have designed and made Pentax lenses exclusively for Pentax, where it would still be a trade secret today, which seemingly "genuine" Pentax lenses would be custom made-to-order designs by Tamron or Tokina, i.e. just made for Pentax alone on Pentax explicit request.
This lens supply source wouldn't HAVE to dry up, if Pentax pays them enough
The problem though is, that the demand side for DSLR lenses will dry up foreseeably altogether, so that it wouldn't pay off any more for Pentax to purchase exclusive lens designs and the rights to patent those. Tamron, Tokina, etc. have all of their engineering under full steam for mirrorless designs. So they would ask for A LOT of money to divert some of their precious engineering time&resources back towards legacy stuff again, if they were asked by Pentax to do that?
So even if custom 3rd party help is still a possibility, I don't think there is a business case left (all external+internal costs versus all estimated revenues), to make that happen in the future?