Five Impacts of Obama's Syrian Failure.

1.   His U.N. Hocus Pocus remark may set back the coronation from US President to UN Secretary General.  There are enough countries that would enjoy cocking a snook at the US to predict this will be overcome.
2.   The Left will be puzzled by Obama's setback but learn nothing from it.
3.   His partial submission to Congress will somewhat restore the balance between the executive and congress.  That this may reduce the use of executive orders to bypass Congress is an un-earned bonus.
4.   US foreign policy will get a major update in the next administration because nations are using the intervening years to realign at US expense.  Canada will be rethinking what matters in its ties with America too.
5.   Little will enter the history books.  Changes to life expectancy, expansion of the internet, and DNA know-how will matter more.

Related:  Conrad Black: "Collapse of American Influence Recalls Dis-Integration of Soviet Union"