This is the sitting duck proposal. No real security guarantees other than the mineral deal. Of course Putin would just wait a few years until Trump is out of office and Russia has rearmed and then just roll over Ukraine and tell the US the mineral deal is off.
If Crimea become permanently part of Russia, that allows Russia to maintain a huge military/naval base that could be used for another war to take all of Ukraine (or at least take control of the southern coastal area through to Odesa to link Russia with Transnistria to set the stage for a further westward push into old Soviet satellite states. And it would cut off the rest of Ukraine from access to the Black Sea.
If Putin really wants an enduring peace, he would agree to security guarantees that would make it clear that any further attacks on Ukraine would mean that the West would stand in to defend Ukraine. Anything short of that will just set the stage for a further conflict.