Many states will be incentivized to keep the compact passes because it means the election stops focusing on a handful of swing states.
Every presidential campaign will have to adopt a 50 state strategy, meaning a lot of states will receive political attention they never get because they aren't swing states.
The legislation has to all-or-nothing precisely because of the effect on political attention. If a state awarded its delegates by national popular vote before the magic 270 was reached then politicians can win that state by maximizing their votes in other states so they would be incentivised to put more focus on the states that aren't signed up if they expect to win the popular vote, reducing the political attention paid to signatories.
When the 270 mark is passed, it has the effect of making every vote equal everywhere.
Aren't the very photolithography machines that all the chip manufacturers use to make their chips all made by like one EU company or something?