This RFC adds generic type syntax to PHP. Classes, interfaces, traits, functions, methods, closures, and arrow functions can declare type parameters; those parameters carry bounds, defaults, and variance markers; type arguments may be supplied at use sites and at call sites via turbofish.
A new syntax for declaring the “set” operation visibility of an object property
Chain method on newly created objects without parentheses
I don't often use generic definitions in docblocks today, but when I do, it's a mess. I think this RFC is the right move at the right time, and cost (both runtime and syntax) appears zero to minimal at best. It'd be really great to see generics land in PHP. It's been a long time coming.