Iso - I'm not sure I fully understand your question.
If you are saying you will offload your auto products to a foundry, then you no longer need to maintain a TS16949 certification for your wafer fab. Just notify your customer of this in a PCN of the site offload. After your last wafers, you can downgrade your quality system to an IS09001 certification and stop maintenance of TS mandated add ons such as Control plans, PFMEAs, MSA etc.
Your subcon however, needs to have TS16949 and you need to have a foundry QA that manages that new foundry site. Essentially, treat them as a supplier but with same expectations as your own fab: you need them to have full TS16949 expectations: All the things your drop in your fab plus one of your own companies overseer that gives them direction, feedback reviews etc.
You can be fabless and still have TS16949. You just have to be clear with your certifying body on the business model and boundaries.
Btw: many foundries will charge you a per $ wafer extra for supplying to automotive industry. This covers their additional inspections, documentation, tighter Cpk requirements.
The other thing to keep in you pocket is that you can be an automotive supplier with just ISO9001.... You just need a customer waiver - tell them upfront and declare it in the PPAP. This is generally ok if your automotive business is small as a % of overall total and you follow the intent of TS16949. In my example, the factories with TS but BU was only ISO.
