That figure of 30% will continue to increase and increase I have no doubt but with a couple of caveats: firstly, I think the lines between mobile and desktop as pigeon holes will become increasingly blurred to the point where no-one uses those terms. Secondly, HTML5 will obviously improve (or a better technology will come along) and thus so will the experience and there will come a time when they are every bit as good as what we play now.
But, in my opinion and based on what I have seen so far, HTML5 slot games aren't ready to do that yet. Sure, they are OK, they look nice, are mostly quite playable but the experience is not as engaging or as immersive and it's certainly much less addictive. Not that I am complaining much about that
I think HTML5 is a learning curve for these companies who are migrating and looking at your original thread the example you give seem like implementation issues rather than something inherently flawed with HTML5.
I think the company who have mastered the implementation best on HTML5 (but sadly not the games themselves) are the team behind bloopers who's name I cannot recall right now. If I screen mirror my phone to my big screen TV it's really impressive. I also have no complaints about netent or yrigdrassil. If your phone and TV are capable you should definitely try the screen mirroring thing if you haven't already done so... it's a good experience assuming it's a well implemented game.