Agree there will probably be no war,but not for the reasons you outline.
The reasons will be because the US is bogged down in Iraq at present,and political oppostion at home.
Iran is approximatly 2.5 times the size of Iraq,not 5 times the size.
Iraq population:67,702,000 (pop growth 1.7%)
Iran population:23,115,000 (pop growth 2.8%)
Yes Iran has bought some new Russian systems,and US will suffer casualties,
but US planners know this and will plan accordingly,end result will be the same.
Draft will not be neccessary,as US will not be alone on this one,any ground attack will only go in after (in my humble opinion) approx 2 mths bombing,(if at all).Also US defence spendin is approx 4.5 to 5% of US budget,with regard to US deficit this will not be a problem as long as the USA remains an attractive place to invest!