1/ as long as the translation of the physical asset to a digital asset is vulnerable to attack, blockchain doesn't really add anything above a centralised database. The only time this is not true is if the underlying asset is itself cryptographic in nature.
2/ You could easily scan a QR code which looks the shoe up with Nike, and shows you the provenance. Blockchain doesn't add anything here, and it doesn't prevent you from owning the underlying asset (unless there's some weird licencing contract when you buy a pair of shoes, which I doubt).