Apple won't be releasing an update to the iPhone SE in March 2017, analyst Ming-Chi Kuo has stated in a note to investors that AppleInsider got their hands on. Unlike any other major smartphone, the iPhone SE's life will be extended past the usual one year period. As reasoning behind such a decision on Apple's part the analyst (whose predictions in the past have more often than not been right on the money) suggests a push to maximize gross margins and spare the true flagship iPhone 7 from internal competition. All that said, the forecast only covers the second fiscal quarter of 2017...
Source: http://www.gsmarena.com/analyst_no_iphone_se_refresh_coming_in_march_2017-news-21474.php