Oh here comes Mr. Lawyer who knows everything about how this will play out!

The possible legal standing to sue is pretty simple. Executive branch issued work permits to these people, and the companies hired them under the impression that because they had government permits, they would be able to hire these employees and count on them being employable.

It's easy to make the argument that these tech companies are being damaged because suddenly the government is deciding that in 6 months those permits they previously issued mean jack. The government is essentially going back on its word and has likely cost large corporations significant expenses in lost productivity, training, and re-hiring.

Unrelated, I know a very skilled legal immigrant (not DACA) who was an irreplaceable specialist to his company (probably making well over $100k) who was deported under Trump's crackdown immigration policies. That's what Trump is doing, turning away highly skilled people in high tax brackets who would like to live in America and would probably like to be citizens.

Companies of all sizes hate uncertainty and that's why the GOP is going to lose a lot of support under the unpredictable Trump administration.