It officially started becoming scarce in 2011, when IANA, and then APNIC, depleted their IPv4 "free" pools, FWIW. Things have only gotten worse from there.

Cloud computing doesn't mitigate IPv4 issues, it just moves it around. The big cloud providers buy up any IPv4 space they can, leaving less for everyone else. The difference is that they then get to collect rent, by the hour, on any IPs their customers use.

Load balancers...yeah, actually that is a valid approach to reduce IPv4 use, assuming you mean the "reverse proxy" variety of load balancer. Cloudflare's proxy service is doing exactly this, on a pretty huge scale. (CLoudflare can then send the traffic on to an IPv6-only server, regardless of the client's protocol.) The downside is, like cloud, consolidating a lot of infrastructure into the hands of a small number of companies.