It’s virtually over. It will be absolutely over when Trump takes a majority of the delegates at the SEC primary on 1 March with a close 2nd or a win in Texas. On 12 & 15 March he’ll win Rubio’s Florida and Kasich’s Ohio.
Then it is definitely over over over. Trump will blow them out in the Northeast States, the great lakes states, and the Northwest states.
After SEC there is no bastion of strength left for Cruz, and after Florida what really does Rubio have?
Super Tuesday is not far off, I guess it is safe to predict that Trump will dominate.