The National Popular Vote Interstate Compact

[True Federalist (진정한 연방 주의자)]

The College will be abolished by 2035. It will hinge on how strong the Democratic majority is but believe me, the minute they reach majority party status, and have enough states, they will pass this so fast that it will cause whiplash, lol.

It will be similar to the 1960s, where a raft of Constitutional amendments were passed under heavy Democratic majorities.

You mean like the ERA and the DC Representation Amendment?

The amendments that passed in the 60's and 70's  had bipartisan support.  Right now, abolishing the Electoral College is a partisan issue.

[True Federalist (진정한 연방 주의자)]

There are more than enuf strongly Safe R States to block adoption of an amendment. While not quite as many, there are also enuf strongly Safe D States to block unless an amendment be bipartisan in support.

[True Federalist (진정한 연방 주의자)]

Surely this would be struct down by the current Supreme Court if it shifted the outcome of the election from Trump to the Democrat.

Why? States are allowed to choose their EC members under Article II, Section 1, Clause 2 of the Constitution:

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Doesn't say anything about having to abide by the popular vote winner of the state in question.
If the state legislature wants to

They also aren’t allowed to join compacts with other states

States reach agreement with one another all the time without there being a Congressionally approved compact. Virginia v. Tennessee, 148 U.S. 503 (1893), held that only those compacts that increase the powers of the States relative to the Federal government need approval.

There's also McPherson v. Blacker, 146 U.S. 1 (1892) which held explicitly that Congress' authority to set the time of selecting electors does not give it any authority to determine the manner in which they are selected. (Bizarrely, for the 1892 election Michigan was divided into an Eastern and Western District which were each composed of six congressional districts. Each congressional district, the Eastern District, and the Western District each elected one elector, so each voter got to vote twice for elector, once at the Eastern/Western District level and once at the congressional district level. Michigan ended up with 5 Cleveland and 9 Harrison electors.) McPherson also held that the Fourteenth Amendment didn't require a popular vote for Electors.