Mate, how are you so confident? O_O
Oh and hang on just a second. The Arabs are going to try invading Iran with foot soldiers? That's gonna be one long ass invasion.
I gather from your comment that you are asking about my high confidence level on ground invasion of Iran by Arab troops since attack on Iran by US is a foregone conclusion.
Now returning to your question there are few points:-
(i) US doesn't have enough troops in the theatre for ground invasion of Iran. Nor any significant movement has been observed for changing the situation.
(ii) US doesn't want to get trapped in yet another war. They want this to be a quick one. There objectives are simple and clear i.e to destroy Iranian war machine and nuclear installations. They could do it through their naval and air assets then why bother risking life of their soldiers?
(iii) An attempt of full occupation of Iran will trigger other powers ( read Russia and China) to intervene which US would never want due to obvious reasons.
(iv) A war b/w ME countries will make them weaker hence more docile towards their 'Godfathers'. ( That is the biggest reason that China and Russia may not intervene in a limited conflict in which no US ground forces are used and the security not the oil wells of Iran is ensured. There are some more elaborate points too which I may provide here when I have more time)
(v) As far as Arabian army is concerned they will not be used to occupy Iran but maybe just to make sure that all the nuclear facilities of Iran is destroyed. Plus their loss of equipments in the war will ensure future orders.