When you level your alts through World of Warcraft content starting when the Shadowlands pre-patch arrives on October 13th, you can do so with Chromie Time allowing you to sync up and experience a full expansion start to finish. Theoretically, anyhow. In practice, it turns out that hitting level 50 will automatically kick you out of Chromie Time after a short countdown, meaning that if you level a bit faster than intended, you could wind up thrown out of the expansion run you were participating in with little fanfare.
Of course, this is probably of secondary concern to the players who were looking forward to the now-delayed expansion launch previously on October 26th. Blizzard has sent an email to many players who have already pre-purchased the expansion allowing them to request a refund on the purchase if so desired. (At least two members of our own staff have received these letters.) It’s still unclear exactly what the new release date will be, although the communication thus far has still implied that it will launch this year.