That is a very interesting question which opens fascinating possibilities.
Disraeli, or the Earl of Beaconsfield as he was called then, died in the early morning of 19 March 1881. Sir Stafford Northcote was the leader of the Conservative Party in the House of Commons, so presumably he would become Prime Minister. [1] The Marquess of Salisbury was Conservative leader in the House of Lords.
In his second premiership "Gladstone had opposed himself to the "colonial lobby" pushing for the scramble for Africa. He thus saw the end of the Second Anglo-Afghan War, First Boer War and the war against the Mahdi in Sudan." [2] I don't know which of these wars would continue if there was a Conservative government in power.
A Conservative victory in the 1880 general election would almost certainly
be followed by a Liberal victory in a general election in 1885 or 1886.
[1] Here is his entry in the Oxford Dictionary of National Biography:
http://www.oxforddnb.com/view/article/20328.
[2] See section headed 'Second premiership (1880-1885)' in Gladstone's entry in Wikipedia:
http://en.wikipedia.org/wiki/William_Ewart_Gladstone.