"Samsung Electronics' System LSI business division is largely divided into four segments; system on chip (SoC) team which develops mobile APs, LSI development team, which designs display driver chips and camera sensors, foundry business team and support team. According to many officials in the industry, Samsung Electronics is now considering forming the fabless division by uniting the SoC and LSI development teams and separating from the foundry business."
The key question is whether Samsung LSI fabless part would be willing to let TSMC be its fab.
I don't believe all the optimistic talk. I think Samsung saw this as a money loser. I don't believe they will be a big customer for Samsung LSI. Here is my assessment. A money losing operation is being spun out to sink or swim on their own. TSMC loves this news. The massive financial muscle of Samsung was holding it up. They lost apple and the fab emptied. That's the truth. Qcom will move over too.
Dunno why articles keep saying "most", as if there are a small number of Samsung produced A10s. There are not. They only did the foundry sharing arrangement with the A9 because they wanted to hedge their bets since they hadn't used TSMC before. Doing two completely different layouts and mask sets for two foundries is very expensive. Not that Apple can't afford it, but why spend tens of millions you don't have to.
The spinoff may increase the chances of Apple using Samsung's foundry, but if they do they'll switch 100% of their volume. For now, TSMC looks to have a better roadmap so a change is unlikely, but to the extent it makes Apple taking their business elsewhere more likely, they might be able to get a better deal from TSMC.