I was discussing this recently with an old friend who I shared a flat with - ooh, 35 years ago. It was the early 80s, but our rooms were painted neutral colours, with lots of grey and green, dark wood furniture and enlivened with some 50s/60s kitsch. Neither of us have changed our tastes much since, though our budgets have improved. So I guess I'll probably be taking my taste for Farrow & Ball, grey and green, autumnal accents and a touch of mid century modern to the grave.
I think the trend for 'flow', with a unified look running throughout the house, will continue. And that probably means grey will survive, because you can either do this with white walls throughout, grey shades throughout, or taupey/cream colours throughout. All of which can look great. I don't think we're going to go back to that 80s thing of each room being a completely different colour any time soon, and I really hope we don't go back to 'hint of a tint' pastels in every room. I love grey, but will be glad to see the back of very cold greys unwarmed by any other colours. These rooms you see where everything is silvery grey rarely work well.
I also love metro tiles - always have - and they are cheap. Done with grey grout, they are practical. I'm not giving them up!
I'm really glad to see the back of shabby chic but I think slapping chalk paint on ugly furniture is a great idea and here to stay. (Caveat: I don't paint over nice wood, and I put matt varnish over the chalk paint rather than distressing it.) It's just so cost-effective. My kitchen chairs were a fiver each from a local restaurant and were covered with a hideous treacly reddish varnish that I would never have got off: but chalk paint has transformed them.
I think travertine bathrooms will go out of style (I pray), and 'boutique hotel-style' oversized headboards, and spotlight hell, and bi-folds, and glass box extensions, and rolltop baths, and oversized TVs, and coloured lights under your bath or kitchen cabinets or whatever. I like the Abigail Aherne 'paint everything inky dark' look but I think it's destined to be short-lived. I think big blocky kitchen islands are overdue a rethink, and that all those people who tell interiors magazines how they knocked down all their interior walls so that they could keep an eye on their children wherever they were, will soon be putting walls back up so they can have some rest from their teenagers.