PNG was never intended to be a replacement for JPEG. JPEG is for continuous tone images. PNG (and GIF) are optimized for line art. PNG replaced GIF because the

PNG was never intended to be a replacement for JPEG. JPEG is for continuous tone images. PNG (and GIF) are optimized for line art. PNG replaced GIF because the latter was patent-encumbered at the time, only supported 8-bit color, and in later revisions only support 1-bit alpha transparency. PNG supports 24-bit color plus an 8-bit alpha transparency channel. WebP, first released in 2010, allows for the replacement of GIF/PNG with lossless encodings and lossy encodings for replacement of JPEG. And unlike JPEG, WebP supports alpha transparency as well. 10 years sounds like more than enough time to optimize previous work and publish it. It's not like existing WebP or even new WebP images will suddenly stop working.