A correction is coming because US market has given over 8 years of positive returns. It is unusual for such a long positive return run. However, the magnitude or average of positive returns for last 8 years is still less than historical index average for S&P 500 index. This seems to indicate that market is not overvalued significantly (at least historically). So I do not think there will be market crash. There may be a negative return in may be 2018 but not a big negative return. I do not think 2017 would be a very bad year. The only way to make it bad is if Trump is ousted. Only then, market uncertainty becomes significant.