I don’t think a hard counter to slide is needed, apologies if it came off that way! 
One of my best games at GenCon 2017 was against slide and I’ve won a sheriff playing Shooting Slide decks, albeit with the crutch of 108 Worldly Desires (pre its justified ban). Slide decks are a necessary part of the meta as they help discipline shooting decks in to including forced callouts/jobs, I’m just conscious that many newer players find it a frustrating match (they frequently find it uninteractive, while I enjoy facing slide as a “puzzle”).
I’d just like to see some cards that help players a bit against slide while trading off some efficiency in other match-ups. Finessing that kind of thing is hard, but based on their work so far I trust the design team to pull that kind of thing off, if they’re indeed interested in pursuing that angle.
I like the idea of example decks as a good starter products: it was great to see several players at GenCon using decks from the playtest team’s example deck lists: Updated Buyer's Guide to Doomtown Reloaded & introductory decks for 2x Base Set (plus expansion decks)
One other alternate format along similar lines that I’ve considered is a 2-1-1-1 format: 2 base set, 1 Pinebox, 1 saddlebag and 4x a particular card. Remixes things for veterans, good entry point for newer players.