oh yeah....they could have marched to Hanover if they wanted too around the right of the Union flank. but a combination of the Napoleonic School tactics (i.e. we will fight our enemy before us), and the fact that Lee wanted to defeat the US man to man (they have said his heart issues were getting much worse as 1863 was wearing on), mitigated that.
It is a given that had Jackson been there and not AP Hill, it may have been much different.
Unfortunately for the soldiers involved, the military commanders of the day, especially the older ones like Lee, were still using the tactics of direct assault that had been in use for centuries. The Civil War was a watershed for new equipment (subs, gatling guns, repeating rifles) as well as an evolution in tactics to manuver and total war.
The most masterful ( and hence successful)use of tactics during the war was Sherman who used the flanking manuver against Joe Johnston over and over, moving ever closer to Atlanta and the sea. He was truly the tactical innovator of the war--Damn his Yankee soul to hell :-)