Hello, my name is Fabian, I've been assigned to support your case.
Thank you for your interest in our products.
Regarding the availability, and the last day to buy. There isn’t any available information about this. We highly recommend to please perform some test with the SLRC61003 version, which is the recommended.
Since there isn't a any significant modifications from the user perspective (pin out, memory, registers) The migration should not be too difficult.
Best Regards,
Fabian