Helicopters rapidly overtake the 1948 Supermarine Seagull

How long would the 1948 Supermarine Seagull have lasted before helicopters took over its job?

Probably only into the mid-1950s, because helicopters could perform nearly all of its intended roles and would displace it by the early 1960s.

Role overlap would doom the Seagull soon after practical naval helicopters arrived. A helicopter could perform about ninety percent of the amphibian's intended work. The type would therefore be in serious trouble by the mid-1950s and effectively displaced by the early 1960s. Its short prospective life follows the rapid postwar move from shipboard fixed-wing amphibians to helicopters.