In deciding to keep my 13 MS85 w/63k miles. Here is my decision tree
1. I can DIY most things outside of HV battery and DU. So costs aren't concerning here. Just parts availability and repair info. Tesla has finally made parts generally available but they do make diag info difficult to acquire (tools, theory of operations, TSBs etc.) but enough seems to trickle out in the community. Do need to put in hobbyist time effort
2. HV battery removal and reinstall pretty much requires a lift so out of reach of most DIYers. Also deadly high voltage once pack is opened so need to be familiar with HV precautions. High failures seems to be contactors, fuse, battery cells/modules/BMS.
3. DU probably mostly the bearing on the induction motor rotor. The complex coolant channeling+seals might leak at some point. Again, Tesla makes design and failure mode info difficult to come by. We've also seen failing slip joint on the rotor (maybe from too many launches? haha) that would require a salvaged rotor.
For #1, if can't DIY, then stuck with SC. Tesla has shown feast/famine patterns on repair costs (Feast whenever they decide to put in some effort). MCU bubble/eMMC fiasco clearly shows this. $$$ for a few years before they decided to make Tegra card and newer supply chain MCU2 option available at reasonably costs.
For #2/#3, have to find the few local Tesla independent who can address these beyond Tesla's crazy replacement costs. Just found Medlock & Sons in my area (Seattle). Grubers is down in AZ, Electrified Garage in NE etc. A few companies harvest Tesla DU/battery for EV conversions (EV West - SoCal, 057 NC). They might also be good source to check for #2/#3 repair options. These guys now all source parts from salvaged cars that Tesla don't sell (battery submodules etc)