I agree there does seem to be a shift happening just now towards late 19th and early 20th century-based novels. I like to read all time period settings depending on my mood, so would prefer to see more of a mix out on the market, but I do think a focus on the late 19th-20th centuries could be an improvement on the recent Tudor fixation, simply because there will be more variety.
Most of the recent Tudor novels (or popular NF) that I've seen have been either based on Henry VIII's wives or Elizabeth I, again and again. I'm fed up with reading the same story, even with a slightly different theory on why things happened. There are plenty of other interesting personalities from that period that don't have much written about them, such as Henry's sister Mary Tudor and Charles Brandon, Penelope Devereux, and so on - although as pointed out in the Forthcoming Books 2013 thread, we are getting one about Bess of Hardwick at last!
Anyway, I think if there is now a big focus on the late 19th/early 20th centuries, there will certainly be a much wider range of subjects and settings and little overlap, unless everyone sticks to the "upstairs/downstairs" theme!
And I, for one, will welcome any new Tudor fiction that doesn't focus on a king or queen