The Ivy League is basically a historical accident. The US has a whole bunch of other incredibly strong engineering schools, from newer private institutions (Stanford, MIT, CMU) to top public schools (Berkeley, UCLA, Georgia Tech). (These are also perfectly competitive in other subjects from English to pure mathematics.)

Historically, engineering and CS was not a priority for the older Ivies, and it was never an issue for anyone else because there were so many strong alternatives.

This department expansion is certainly good for Yale, but the effect it will have on the top engineering education in the US as a whole is marginal.