That is what they are hoping for...I think 2/3rds of the states need to pass the law....
No, 3/4ths of the states need to approve Amendments to the US Constitution. In short, it'd never pass.
No, this is a proposed compact between the states. It only has to be approved by each state. Each state has the right to allocate its electoral votes anyway it sees fit. The proposed compact can be entered into and withdrawn from by its member states.
"Besides California, legislation to create a compact was introduced this year in Colorado, Missouri, Illinois and Louisiana. Proponents are pushing to have similar bills in all 50 states next year."
This is an end run around the electoral college, which would require a constitutional amendment to change. This compact would give the bigger states more power to determine the outcome.
Constitutional amendments need 3/4ths of the states. So they know that will never happen.
It does not matter how many states pass such a law, to the extent that it affects the power of non-cooperating states in the selection of the President, it is an unconstitutional confederation (Article I, section 10).
OF course, 2/3 of the states can call a convention, amend the constitution (If 3/4 of the states agree), and thereby git 'er done.
But the California proposal is unconstitutional.