Trump being elected will not result in conservative Supreme Court justices.
Point 1: Supreme Court nominees have to be confirmed by a majority vote of the U.S. Senate. (Article II, Section 2 of the Constitution) But, under current Senate rules, Supreme Court nominations can be stopped by a filibuster supported by 41 senators.
Point 2: Republicans currently hold a majority of 54 senate seats. Democrats have 44, and there are 2 Independents who caucus with the Democrats.
Point 3: Republicans have to defend 24 senate seats; Democrats only 10. Of 10 senate seats in danger of flipping, 8 are Republican. Chances of getting to 60 to prevent a filibuster are infinitesimal.
Point 4: Trump doesn't much care if Republican senators get elected. Neither Trump nor Pence are backing John McCain of Arizona or Kelly Ayotte of New Hampshire (in their primaries), and Trump has been critical of both. Further, Trump isn't campaigning or raising funds for Republican senatorial candidates.
Point 5: Trump's persona and campaign style of personal attacks have made electing any Republican hard.
Point 6: Trump has flipped on so many issues, the odds of staying with his conservative justices promise are low.
Even if he wins the presidency and keeps that one promise, there's no way Democrats will confirm any conservative court nominee. The Democrats have shown they know how to play political hard ball both with a majority (Obamacare) and a minority (budget votes they don't approve of). And they will have the mainstream media backing them almost unopposed since Fox has damaged itself in the eyes of many conservatives and Republicans with its pro-Trump rationalizations.
The best hope is that Trump will be able to confirm "centrist" (read: liberal light) justices. Hillary will also have the same chance because Democrats will not have 60 votes to prevent a filibuster in the Senate. But, since Republicans don't vote their conscience but vote for political utility she will probably be able to get liberal moderates through.
So, your choice will be liberal light at best and probably liberal moderate. Is it worth the shame and danger of backing a vile, unstable candidate like Donald Trump?
Note: Post has been updated to reflect filibuster numbers. Two-thirds vote of Senate is only required on treaties.