I'm always a little amazed at how short-sighted some people are. The claim "Apple and Android already won the smartphone UI war" is idiotic on several levels. First, because there is *no such thing* as a smartphone UI war.
Second, Apple and Android *both* use derivative, rehashed permutations of the same tired Xerox Parc UI paradigms we've been using since the 1970's. Do you seriously believe there is nowhere to go in UI design than with endless rehashes and minor adjustments to that system?
Third, It is an historical fact that 90% of significant changes that ever occur require time to take effect. When the MOUSE debuted, reviewers hated it and said it would die, unused because the keyboard was better for productivity. When Windows 95 debuted with the Start Menu, people *hated* the Start menu and called it every conceivable terrible named, and swore it was the death knell of Microsoft. When Windows XP arrived, it was welcomed by slow sales and poor reviews, with a lot of tooth-gnashing by people who hated having to learn the vastly different underpinnings of Windows NT vs 9x. When Microsoft launched the Xbox, people called it an "also-ran" and claimed MS could never find success in that space. I think we all know how those things turned out.
The Modern UI only came into major usage 2 and a half years ago with Windows Phone 7, which was a niche product. It's now found in a major OS that's sold more than 100 million licenses thanks to Windows 8, and WP8 is now finding itself growing by large numbers and will likely take hold of 10% of the smartphone market *this year*. The effect is called "Product synergy," and as Windows 8 permeates the market, WP8 will itself become more "familiar" and something customers reach for.
The long and short of it is this: It would be a DISASTER for Microsoft to abandon the Modern UI, and a tragedy for consumers if they did. More importantly, anyone who's followed Microsoft for the last 20+ years knows very well that they *do not play* the short-term "Me, too! Me too!" game. They are masters of the long game, and they know what they are doing.
Yes, there are many areas that need to be improved in the modern UI, especially on the phone. A notification center isn't one of those things, really (as some have already pointed out, the Start Screen IS a notification center for Live Tile enabled apps), but its current implementation does have a problem: If users don't pin their apps (and many don't, as they prefer a clean screen), they won't see their notifications. I see two ways to address this problem: 1. Add a Live Tile that aggregates all notifications and scrolls through them. Make it an app that you can tap to get a full list, complete with shortcuts to the app associated with the alert. 2. Change the behavior of the App List such that if any apps have pending notifications, they automatically are filtered to the top of the app list, in order of most recent notification activity, until the user addresses the notification. Both these ideas would work, and both honor and maintain the Modern UI design language, which is absolutely *imperative*.
I own an Android tablet (Samsung Galaxy S2 10.1) and I moved to WP from iPhone, and I'll tell you unequivocally: The LAST thing Windows Phone needs is to become more like Android or iOS. ESPECIALLY Android, which is a bug-riddled turd of an OS.