I don't think the law needs to mandate DRM-free purchases at all.
If a company wants to operate a model where they sell you something but they will store/"maintain" it for you to use at any time, they are free to do so under the conditions that they define.
But if they decide at one point that it's no longer economic for them to store/"maintain" your goods, they should be required to return them to you.
Right now, they simply inform you that the goods you purchased are no longer available to you as it no longer fits their interest to maintain them. And that's something that should be legally challenged in my opinion.
If a company wants to operate a model where they sell you something but they will store/"maintain" it for you to use at any time, they are free to do so under the conditions that they define.
But if they decide at one point that it's no longer economic for them to store/"maintain" your goods, they should be required to return them to you.
Right now, they simply inform you that the goods you purchased are no longer available to you as it no longer fits their interest to maintain them. And that's something that should be legally challenged in my opinion.