Trump will not be going 3rd party because he will be on the Republican Ticket for President of the United States with Ted Cruz as his running mate.
Trump will win New York electoral votes in the general election. It's going to be an early victory for Republicans come next November 2016, mainly because Native Son Trump will win New York electoral votes over Carpet Bagger Hillary.
If we have to have a NY Democrat for President, then by all means let it be Trump.