Not all sanctions are going to be lifted, if there is a deal. Which is a big if.
They are not even going to be lifted to begin with. That requires congressional approval, and sorry, but that just aint happening right now.
Obama can SUSPEND them for a certain duration. But that is not the same as lifting.
That is not an optimal economic or political climate for foreign investors. However I believe Iran is such lucrative and large market, that we will see some companies take some risk anyway.
Then after some years, the political climate may have changed in the US so that congress can perhaps permanently lift them, but its doubtful.
I think you all have to prepare yourselves for a grinding process and bumpy road. Just as the implementing of sanctions against Iran, was quite a long process, likewise Iran's integration to the world economy is something that is going to take at least a decade, if not more.
There are other factors too. The economic center of power is shifting away from the west, towards the east (in particular China).
Meaning the US is not going to have as much weight, as it once did, in the world economy.