[dragonwriter]

> Or irritate a long term user base?

How?

> PHP has been very successful long term, largely I would argue because of maintaining almost complete backwards compatibility.

Gemification of the standard library has very little impact on backwards compatibility; moving out of stdlib into default gems. Moving to bundled gems is transparent to code but has to be taken account of in build infra, moving out past bundled gems is where it would become visible to consuming code, equivalent to being evicted from stdlib before gemification.