With the entry of Google Scholar, the access and value-add businesses are divorced. The cost of the underlying access has reached zero. But the reason Westlaw and Lexis are still huge is because they do provide value-adds.
So this talk of opening up PACER is really missing the broader access point - the opinion access problem is largely solved via Google Scholar. PACER documents may be opened up, but they are not useful to lawyers in anything other than some basic docket scenarios.