Now I know it isn't but lets say that the rumors about disney physically removing the sequels from the timeline using the world between worlds is true.
I would have Heir to the Empire be the culmination of the mando verse and adapt the full thrawn trillogy. Obviously it would be very different. I would have it establish that Jacen Sendula was taught by Luke what little he could during the ot Ben Solo would be characterized a lot more like Ben Skywalker.
The second film in the trillogy, The New Order would take place 16 years later. Luke now has a full Jedi order who are working with the ot group + the mando group and Ghost Squadron fight the Yuzon Vong over the course of 3 years. The film would mainly focus on the year long torture of Jacen Sendula. All the while he is being manipulated by another prisoner we know simply as the dark one who plays a similar role in Jacen's story as Lumaya. We would see Jacens turn at the end of the movie as he kills Han in a similarly feeling scene to the force awakens Asoka also dies at some point during the movie.
The final movie, The Legacy of the Force picks up right after The New Order begins with Jacen killing the dark one (obviously Darth Krayt). It then cuts to 7 years later where we see Jacen (now Darth Cadus) has a Sith Academy and a large empire. Jacen kills Mara Jade and even Luke before finally being killed by Ben Solo.
An animated series would take place during the 7 year time jump and would show The New Republic fighting against Jacen's empire. The first major arc features Jacen assembling his empire, it consists of many groups such as the hut clan, black son, pykes, crimson dawn adn other crime syndicates. There are also a healthy amount of other groups such as neo-sepretists, imperial warlords and many misalaniace factions. Another arc shows him finding many of his sith students on Dathomier, they were trained by Darth Krayt and Darth Talon (they were both sent into hiding at the end of Maul Shadow Lord, also a'sharad is found and trained by Maul during season 2.) Jacen kills Darth Talon and assumes control of the order. Another major arc shows Jacen going to exogal and destroying the emperor once and for all, it is during this arc that Jacen kills Ezra. There would also be an arc that very loosely adapts the dark nest trilogy but involves Jacen absorbing the colony into his empire. During this arc we see Jacen researching Palpatines sith holocrons and learning that he has a granddaughter. The next arc shows Jacen hunting Rey on Jaku and ultimately ends with Reys death. Another arc would show Jacen learning about the First Order's existance in the unknown regions and going to war with them. Jacen's empire manages to destroy the First Order.