Good luck Library Addict. I don't blame you for a bit of optimism, but it seems to me to be crystal clear that they are dumping Adobe. Offline reading will be only through either a web browser or the app. If you want to read on an e-ink device except perhaps one running Android bad luck. Also bad luck if you want to keep a backup once they dump ADE. E-Ink Kobo's or Kindles. Forget it.
We can only guess as to their motives for doing this. Certainly I doubt Adobe ADE licenses are particularly cheap, and this could well have played a role. Particularly if they are under financial pressure, which is also quite possible given that the Romance genre has come to be dominated by Indies. As for piracy playing a role. I doubt it, but it is not totally impossible that it is playing a role, or at least that Harlequin thinks it is. It is not inconceivable that they are losing many sales to Indies but are instead blaming piracy. Personally I doubt it is going to help them and may well cause them serious harm. Their reputation is in tatters after their treatment of authors in relation to royalties, and I suspect they will alienate many readers with this move. If I was one of their customers, which I am not, this would do it for me. Quite apart from my own strong preference for reading on e-ink devices the fact that I would not be able to back up my purchases alone would be enough for me to part ways with them. I would not be prepared to trust either in the financial solvency of this company or the dubious ethical standards they have demonstrated in the past to keep my purchases accessible.
My admittedly biased recommendation:
https://www.youtube.com/watch?v=ohXI3po8hK0