Interesting, but I feel it overlooks one key point.
Where we are now and where we came from…
I have been leveling since 2004, there was no speed train for your main character thru the myriad of expansions. That toon may have been swapped out over the years for a different class, but you still did the entire content available. It wasn’t a big deal when you were in WotLK to bring an alt up thru Vanilla & TBC to get to the current content, but now you would never want to level up an alt that way to the most current content.
I think Chromie Time was a nice attempt to offer the different expansion content to leveling, but even then, you outpaced the content and didn’t even finish the expac before hitting the cap needed to enter the new zone. I currently have 6 warlocks leveling thru 6 different pathways for nostalgia story content. Its been fun to revisit some of these old zones, but one thing is clear…its a ghost town leveling these days. The player base is at the new content and you need to catch up to be able to really interact with other people.
I think Exile’s Reach was another good attempt at a tutorial for new players. It got you to level 10 with “gear” and if this was your first toon, you went into the BFA storyline to try and get you acclimated to the overall story and major characters.
With the Story arc of Chromie and the Timeways, I feel there is a good opportunity to create a “new” leveling method that takes you thru every expansion, giving you a taste of all the old contents greatest hits. This would enable new players a better understanding on the lore without feeling they missed something by not playing 15 years ago…
A good example of this is BFA. Unless you played both factions, half the story never made sense to you. You were in dungeons and raids without certain context to the players. (I always thought they needed to offer the other factions zones to you as a “spy” if you didn’t want to create an opposing faction character & level it high enough to even get into BFA)
There is a ton of content this expansion outside of Raids/M+/PVP. I feel they have done a really good job on maintaining content release timely. You just need to make sure you have found all the ! on your map. (Some are gated behind Renown, which was the tradeoff for not saddling us with a “Borrowed Power” grind. Renown grind was always optional.