I'd hope for a modest update with 8th gen and USB-C (wonder if they'll keep Surface Connect for backwards compat, or have a reverse-dongle for old docks to connect to new devices?), lifting the minimum RAM up to 8gb, and my leftfield idea, making the case colour an option so people can have e.g. all-cobalt machines, the Laptop looks so much better for it, and it's a shame the Pro makes you have silver when all the accessories come in all the colours.
I hope they can do it with quicker cadence than the usual 18 months, there must be a lot of tech enthusiasts who turned down the 2017 for the lack of USB-C, I think it was a fairly big mis-step for that refresh.
They had what looked like a bit of a firesale on i5 2017 models just now and I was sorely tempted though, but I only get a new laptop every 5 years or so and I don't want to get the last model not to embrace USB-C, so I'm waiting again...