Star Wars question, will the Ashoka Tano Show Retcon The Sequel Trilogy?

We don't know anything about it yet, but I've read that as of now they have no intention of retconning the sequels and they just plan on making a ton of shows that take place between the trilogies. 

No.  The Mandalorian and the other shows set in and around this time period are meant to bridge the gap between Return of the Jedi and The Force Awakens.  This is a roughly 20-30 year period, and they'll show how things changed from the Rebellion's win at the Battle of Endor to the ongoing war we entered in The Force Awakens.  Disney is working on creating a new universe and continuity.  All of the films in the new trilogy as well as the new TV shows are canon.  Some of the previous TV series are canon.  Most of the previous books and comics are now non-canonical.  Some may be altered and added to continuity - rumor has it that the Thrawn trilogy will be tweaked and made part of the current canon, for example.

There is nothing to indicate that any of the announced Star Wars shows will retcon the Sequel Trilogy. 

There is also little to no information that indicate what the shows will be about.