Some quick napkin math on the current MAC vendors database: 46 bits of a MAC address are reserved for universally administered unicast (i.e. a globally unique MAC assigned to identify a device). So far we have assigned ~570 billion addresses via 24/28/36 bit range assignments for the same purpose which represents a little under 1% of the space. So nothing urgent, though if we stuck with Ethernet as much as we use it today then in <100 years I wouldn't be surprised if we were "out".

At the same time there are also 46 bits of locally administered unicast addresses and, unlike IP, Ethernet addresses only care about the local network (and this isn't a "because we've co-opted them to to save space just like NAT broke IP protocols" rather the design intent of Ethernet). Even if you had 10 billion LANs with 100 devices each and they all used this random non-unique assignment there would only be a ~50% chance there one or more devices would have a collision.

The only real advantage I've ever been able to find of programming in unique MAC addresses vs random MAC addresses you can look up what company the MAC was assigned to. It may seem like there is a risk random assignment can be done poorly (e.g. not very randomly) but honestly the same risk exist with assigned ranges as seen by network vendors cheaping out and re-using their MAC blocks (which is significantly more likely to conflict than if they just used random locally administered addresses in the first place).