There are publishers now who don't give advances or royalties but share the book's profits equally with the author. Do you think this would be a better deal for authors?
It's a different deal for authors, and possibly a better one, but it's really too early to tell. I think what's good about some of these contracts is that the profit-sharing arrangement indicates more of a partnership between publisher and author than the previous overlord-underling situation (as authors have perceived it - in truth authors have always had the power, because there is no publishing industry without them and if authors collectively decided to not be published by publishers the whole industry would collapse).
What's also good is that a lot of these new contracts are for limited terms - three years, five years, nine years - not life of copyright. A limited licence puts the onus on the publisher to 'perform' within that time frame, knowing that their performance will be reviewed at the end of the licence. It also means that either or both sides have a way of extracting themselves from the relationship if it's not working, and that way is bloodless - the licence comes to an end and off you go.
From my unofficial surveying of authors it seems that novelists (for any age) are the writers least likely to be upset about not receiving an advance. They've already committed time, energy, brain space and love to their novel - now they just want it out in the world. If they get a cash money advance for it, great. If they don't, well, they'll get royalties once it starts selling. What's more likely to interest them is editorial and marketing/publicity/sales support - these are the things publishers can do for authors, often very well, that authors struggle to do for themselves, whether because of financial or time constraints.
We're likely to have the traditional publishing models for a while, and they will peacefully coexist with the new models; some authors will be able to choose between them and some won't. Sometimes the author will decide that it's better to not be published at all than to take an arrangement that isn't right for them - and it may be that it's the traditional publishing deal that ends up being the arrangement that isn't right. We'll just have to wait and see.