Is this about replacing one monopoly with another? It is slowly starting too look like in the early 00's, most developers are starting to support only chrome, with no testing in Firefox or latest IE. On Android it is even worse, no one is testing with Firefox Mobile (Fennec) - this is WinXP-IE6 all over again.
The other thing is that major libraries (CSS, JS: jQuery, bootstrap, React) make sure they work on all browsers so you don't have to worry about that part.
The winXP-IE6 was hell because that never happened, you always had to changes to make it work on IE6 and some other changes to support IE7 and so on.