So I am only level 11 and greatly enjoying my Destruction/Conjuration Mage. I just became Arch-Mage and a little ways into the Main Quest. My question is......I am considering playing this character as long as I can and then at a high level after the main quest have him refocus his skills. Not sure what to at this point. Point is I would love to try some other skills later and just do some side questing with my same character but using different and new skills. Consider him the Incredible Hulk. He fights with a dagger/bow and light armor only and when things get really tough he can shed that and cast Firestorm and follow it up with a couple of Storm Atronachs. Thoughts?

You can make a Jack of All character if you want, but it is more fun to specialize as it forces you to approach each situation differently with each character.

Focusing on new skills shouldn't be all that difficult. You gain experience with anything that you use. I'm just not sure how the leveling would play into it. I know that leveling takes long at higher levels and so that would probably play into any perks you may want to go after. But since I have not done what you are talking about I am unsure of the specifics.