I hope you can get 10 years out of it, I'm guessing it depends on your climate and rainfall and how well that berm will drain off instead of in.
As long as you're factoring in rebuilding into your designs, I'm sure it will turn out alright.
Paul referred to
Mike Oehler's
underground house designs when he designed wofati. I think (though I might be wrong) that they ended up using some kind of plastic liner to create an umbrella to shed
water off the structure.
I haven't done any earth/underground style building so hopefully someone else with more
experience will give you some feedback. If not for now than for when it does come time to rebuild.
For now I'm jealous of your root cellar! Having one would make storing potatoes, sweet potatoes, pumpkins, carrots, etc so much easier.