Longevity of my character?

I've been playing a templar for a while now and just made it to cruel difficulty. I'm mostly shooting for a tank/concentrated damage dealer. I've been using glacial hammer and molten shell. So far, it has been pretty much smooth sailing. I'm wondering how long this can continue.

At what point does tanking become unrealistic? So far, I am having no problems 1 hitting most white creatures.

Also, how do I link you to my passive tree?

Edit: Found it http://www.pathofexile.com/passive-skill-tree/AAAAAgUABLMFWxBpFE0ZLiSLJ-0wlzKJOYo9D0E_RtdN2FHmXcZgbXKpd-V8u3zZfVOBK4FvgpuDOIuMjHaUh52AnjyiAKyqtC-0-cT21I_dBd3z37Lhc-0g8B_z3fcy