Longstreet assumes Jackson's place in Confederate martyrology with a greater claim to it, Jackson destroys his own reputation when his strategic gifts but tactical mediocrity bumps up against both Meade and Grant. Jackson might be the one to have a Shad Bake expecting his usual magic to work at say, Spotsylvania's equivalent and then he sees his entire line collapse.
The ANV is just as unbalanced without Longstreet as it was without Jackson, arguably moreso. Jackson is like Sherman: strategically he's the best there is at what he does in the CSA, tactically he varied from mediocre to crapsack. The Jackson of Cedar Mountain at Gettysburg would turn it from major victory to curbstomp. The Jackson of Chancellorsville would leave it at OTL-level smash-up. Jackson, like Longstreet, would object to the fight and have no headway against Lee's Hulk Smash approach to fighting.
Longstreet was the best tactician in the Confederate army. At Second Bull Run and the Wilderness he was the only Eastern CS general to roll up Union troops with regularity. Jackson's strategic sense could compensate for his tactical weaknesses but if he decides to repeat his major risk-taking moves from a sense of invulnerability with a real tactician he's asking for a whipping. An interesting question is whether or not Jackson would want to concentrate at Chickamauga or not. If he doesn't, Rosecrans wins that battle.......