Getting warranty and service work in Tucson would be problematic right now due the reductions in staffing and additional protocols at the border. The current wait to drive through can be many hours. I know BMW owners from Sonora who used to bring their new cars up here to pay for work that would be warranty in Hermosillo because the quality of work at the dealer in Hermosillo was laughable. I expect that they have no choice but to have their cars serviced there now that the border is closed to non-essential travel.
I agree that US service crossing the border is very unlikely. Does anyone here have any experience with towing a car across the border at the moment?