While the fully envisioned Kasserine would, as you suggest, surely have created a lot more chaos and mayhem among the Allied forces advancing from the west aand allow a stiff punch to Eighth Army advancing from the east, that would only delay the inevitable. Hitler may have tended to over-reward this success, and devote still more men and materiel to the theatre. Then, an even more Axis resources would have been lost in the inevitable surrender. The Allied air and naval superiorities were simply too large to overcome. The Axis supply problem would only be made worse with still more troops and ordnance to sustain. The Achilles Heel of the Axis was over-extension. You'd think Hitler and Mussolini would have learned from Stalingrad.
Where would this re-inforcement come from, save the East Front? But Hitler was already consumed with gathering up every possible stone to throw at Kursk. While retaining at least a toe-hold in Africa was vital politically to keep Italy in the war, it was also militarily impossible.
The best course would have been to use the time and space gained by a greater Kasserine victory to:
1. Gather up every morsel of abandoned Allied supplies that was possible.
2. Do a "reverse Dunkirk" while the Allies were still in disarray. Get every man and machine "Out of Africa". (What a great phrase for a title! Someone should write a book/.make a film called that!)
3. Organise an in-depth defense of Sicily, Sardinia and south Italy.
After all, the experienced, skilled soldiers of D.A.K. and the fruit of the Italian military died or were dragged off to prison camps in the ensuing 6 months. Those men could have stood yeoman's service with the shorter lines of communication and supply. The rest of 1943 could have been much bloodier for the Allies.
However, the ultimate end of the war would not have changed. It may have lasted longer, but only by a few weeks, at best.