FYI, you might also take note that Electrified Garage is now claiming to provide rooting service. Not sure how good or reliable there service is but it might be an option.
eMMC Repair/Upgrade for Model S and X + Optional Root Access
Edit: oops your talking about a Model 3, not S.
I think it is great that 3rd parties are offering the eMMC upgrade but $1,500 seems steep considering they aren't even taking your MCU out or putting it back. Wouldn't it only cost ~$500 more to have Tesla replace your MCU and give you a full 4-year warranty on the whole thing? (So your screen would get replaced as well.)