Retrospective:
The Obamacare was not constitutional unless considered as a tax. The mandate made the law a tax.
The mandate is gone. In theory with the mandate gone, the remainder is unconstitutuinal.
Why is there not a law suit rather than floundering around with out success in the Senate?
1. The mandate is not "gone." The 2017 tax reform bill reduced the penalty/tax to $0, but other than that the Affordable Care Act remains unchanged and the penalty/tax provision is still in it.
2. There are so many ways to win a lawsuit over various provisions of ObamaCare. Some plaintiffs have been doing just that ... the Hobby Lobby case that nobody talks about, for example. The Roberts decision -- while I hated it -- only applied to one very specific part of the law (the individual mandate). The problem is that it's not always easy to find a plaintiff who has the legal standing to mount a credible case. Here's why: If you were to file a lawsuit against ObamaCare tomorrow, what would be the basis of your case? You'd have to demonstrate that you were harmed in some way, and that's not as easy as you think. Since ObamaCare is all about regulating the health care industry it's really just state governments and insurers who would have the legal standing to challenge those regulatory provisions.