I agree, but what you say is a threat for the medium term future.
The immediate threat is one of intelligence operations, targeted bombing raid / missile strikes, potential special forces or commando raid, assassinations of scientists and engineers, flood of propaganda, attacking Iran's technologies and power grid through cyber warfare.
These are the places of most pressing concern, Iran must
-counter the propaganda and generate its own,
-protect at all costs scientists and engineers
-invest heavily in cyber defense
-and anti-aircraft weapons
-missile defense.
Not only are these the most pressing concerns from the US, but furthermore it seems unlikely that the US will move forward with more aggressive strategies if they cannot get their covert operations / terrorism / cyber warfare to be effective in weakening Iran's defense sufficiently.
Furthermore, the Israelis will rely solely on covert operations, propaganda, and electronic warfare given the strategic limitations.
Secondly, the US leaving Iraq and Afghanistan also provides great opportunity for Iran. Sure, Iran won't have targets there, but if Iran can establish its authority in these nations, then Iran can hit other coalition forces based throughout mesopotamia and the Indian subcontinent.