SonyAlphaRumors indicates it got word Sony plans on launching Mark II versions of some of its earlier E-mount lenses. Some of the lenses are almost a decade old, so this might seem natural, but there are a few other factors that play in.
Sony is said to have jump started its early lens lineup by hiring out lens manufacture to third parties, in particular Tamron. As Sony has developed some of its own innovative manufacturing methods – as revealed by a series of LensRentals blog teardowns – it may want to exploit these, and potentially larger margins.
Sony also developed some odd cooperation agreements with Zeiss in the past, putting the German company’s logo on a lens – likely made by Tamron – as a Sony offering. Zeiss a couple years ago made a point of telling people it was not going to do that any longer. New versions of those lenses will likely be significantly redesigned as in-house products.
Finally, Canon’s recent stream of RF lens releases shows several technologies baked into the lenses that are exploited by the new R5 and R6 bodies. People shooting the RF 85mm f/1.2 back in the EOS R days didn’t realize they were holding a tube full of accelerometers that would later be harnessed by the new R5 to provide a silly level of in-body image stabilization (purportedly 8 stops) with a lens that didn’t have image stabilization. That clever trick shows that to be a big boy in the pro camera world, some things need to be baked in, not farmed out.