I have the same worry. Page downloads content as some encrypted binary blob, displays it using <canvas>, impossible to block advertising or copy text.
However, at the end of the day, content providers have to make their content available in plain HTML format in order for search engines to index it. If they did the above without offering a plain HTML alternative, they'd lose traffic from search engines. But, if they are offering that format to search engines, they have to offer it to us too.
(Okay, they could lock it down so the plain HTML is only available if User-Agent = Googlebot/Bingbot/etc and source IP is coming from Google/Bing/etc network. But, will the search engines let them get away with that? I would hope Google would refuse to index it on the grounds that their crawler is getting something very different from what the real user sees, but I guess that's their decision.)
However, at the end of the day, content providers have to make their content available in plain HTML format in order for search engines to index it. If they did the above without offering a plain HTML alternative, they'd lose traffic from search engines. But, if they are offering that format to search engines, they have to offer it to us too.
(Okay, they could lock it down so the plain HTML is only available if User-Agent = Googlebot/Bingbot/etc and source IP is coming from Google/Bing/etc network. But, will the search engines let them get away with that? I would hope Google would refuse to index it on the grounds that their crawler is getting something very different from what the real user sees, but I guess that's their decision.)