So does this look like a case that they would probably take up?
Federal courts do not generally defer to state court's interpretations of federal law. The reason is pretty obvious, the U.S. cannot have fifty different interpretations of federal law by each state court. Any state court that attempts to interpret the U.S. Constitution, Treaties, Laws of Congress, federal administrative decisions deriving their authority from federal law, or diversity of citizenship issues creates a "federal question" that is necessary for Scotus (or other lower federal courts) to review a state law, court decision, etc. There is also the issue that the decision was 4-3 at the CT Supreme Court which indicates that a slim majority supported the plaintiffs' attempts to compel discovery of Remington's marketing practices by not dismissing all of the claims against Remington. The appeal in CT dealt with whether Remington was shielded during the lawsuit from claims by the plaintiffs. The Supreme Ct. of CT decided not and was to allow trial court proceedings such as discovery etc. to advance.
On a federal question generally the Supremacy clause attaches. This case has the potential to muddy the waters, so to speak, of what tort law protections the Protection of Lawful Commerce in Arms Act (PLCAA) offers third parties. State appellate courts have generally deferred reluctantly to this law in previous lawsuits so my suspicion is that this case will be viewed by the Supreme Court more as a judicial federalism type case rather than a pro- or anti-gun decision. Generally the federal courts and judges prefer unified of interpretation of federal laws so you might even see one or two of the more liberal justices siding with the defendant here due to potential adverse precedent to other federal laws that the liberal justices like such as Title IX interpretations etc.
Some diversity of citizenship cases get a little weird and this is one that involves both state tort law and a federal law passed under the Commerce clause authority that dictates how states may address liability by third parties such as retailers and manufacturers of firearms. This is not unprecedented btw as such things as nuclear power plants, aircraft, etc. have some degrees of federal tort protections from state tort laws and absent Scalia on the court, have also decided that state court tort decisions can violate the U.S. Constitution in instances of excessive damages ( BMW v. Gore). Justice Scalia argued along with Justice Thomas and Ginsberg in their dissents that the federal government had very limited powers to monkey with state tort decisions.
The idea of joint and several liability under tort laws is to allow recovery from third parties to redress the injury suffered by the plaintiffs (deep pockets usually). However, often activists use class action suits to both fund future activism (smacking of barrantry--which is litigation designed to pay the attorneys rather than benefit the plaintiffs of the public good), punishing disliked organizations and companies via the bad press and financial costs, make the company involved settle such as adding restrictions to resellers and marketing and payment of lawyers fees, and sometimes just for the discovery process to lay the grounds for future litigation. See this NY Times story about the case that focuses on the plaintiff's goals for discovery for example
https://www.nytimes.com/2019/04/08/nyregion/sandy-hook-gun-lawsuit.html
As much as anything, this lays the groundwork for Dems to try to repeal the law once they regain power in Congress and/or the White House by focusing on "evil gun companies and retailers". What these folks hope to do is bankrupt the firearms industry the same way that tobacco was attacked which also gives the attorneys involved gobs of money.
Since I suspect that the litigation is getting funded by deep pocketed billionaires with an anti-gun fixation (cough short former NYC mayor guy among others), it is viewed as conscious raising with the possibility of a win. Whether the suit wins or loses ultimately, it was designed to generate bad press, keep the CT massacre in the public eye, advance Democratic policy initiatives in building support to repeal the law, and put gun manufacturers and retailers on notice of future litigation.
