With Mapbox focus shifting, it appears, to car navigation - it's great to see disruptive innovation coming from new places. (Notably: they have continued to invest in Tippecanoe which is awesome).
Felt is one of the major services that I believe uses the PMTile approach behind the scenes and they won't be the last. With PMTIles vector tile hosting is arguably easier, more convenient and an order of magnitude cheaper then going with Mapbox (especially if you don't need fancy projection / 3d support and are ok with MapLibre). While you could always bake tiles with Tippecanoe you still had to struggle with vector tile hosting hosting. While powerful it was way to confusing and expensive. Mapbox in my opinion left the door open in how they approached tile baking with MTS. From my perspective, this is the most important contribution to the open mapping space since the introduction of vector tiles and Mapbox GL / Map GL. I've been an avid Mapbox user since getting alpha access to Tilemill.
