Writing this as a personal opinion piece for personal entertainment (and in case anyone else is interested). Please don’t take as legal opinion. From a UK perspective, for digital goods (like video games) where rules are bit different from physical products and services):
Fundamentally OW2 was free, so whatever acti-blizz do to it - there’s no damage or loss to you if planned/anticipated features were removed. A game can be shut down and they don’t have to refund people. Hence a lot of cash shops stay open until few weeks before a game goes offline forever (without any successful challenges in europe I think), recent example EA shutting Apex Legend mobile at 90day notice) and I think there’s been tighter ones. That’s the bar you’d have to surpass to prove damages - complete loss of availability at 1-3 months notice.
Other option would be if your purchases were because you were promised or had reasonable expectation that your purchase would relate to future content (for example unlocking a feature) and were mis-sold. You’d have to carefully scrutinise the OW2 marketing material, but I doubt you’d find anything, the goods and services you purchased were likely solely associated with the current version of the game. Didn’t follow the OW2 launch but I think for example when purchasing the OW2 early access pass thing you knew it gave access to the existing version of OW2, and knew/expected no new PvE content was available or would be provided during that service.
If someone can conclusively prove acti-blizz had no expectation they could deliver on their launch promises when they were making them there might be a case for false advertising? But that’d likely be a fine from advertising/trading regulators as a deterrent action proportionate to financial benefit (and market harm) caused by acti-blizz’s miss selling, you probably wouldn’t see a penny.
…turns out I can’t link anything but you can google oft1519 by CMA “Principles for online and app-based games”