Zd,
Which gedolim? Please name and cite references.
Besides, your comment makes no sense, how will making Sunday a day off change what the chilonim will so on Shabbos? Going to work does not seem better than what they are doing now.
It willhowever make working even more difficult for religious people. If the day of rest, the day off, is not Shabbos. I am sure that there will be chilonim who will use this as another reason not to hire religious Jews. And I am sure you will defend them as well.