what holds Surface RT back is the lack of development for desktop RT apps. If MS would open that up (as well as win8 desktop apps in the store) then it would change a lot very quickly for the platform. Nothing particularly wrong with metro, it has it's place, but let's not neuter a product that is perfectly capable of something more. Droping the price a little bit would be nice as well.
Surface Pro is great, and is selling great. Problem is that they are not building more. Part of this is because they are conservative and do not want to jump all in on something that actually could fail. Part of this is because they are relatively new in their relationships with their hardware partners and it is going to take a little time to get them to be willing to ramp up production at a low price. Part of the reason is that they know that Haswell is going to have much better parts for Tablets, so they do not want to go full bore until they have the product that they want, rather than the first revision product that is merely fast enough to make things work. Take your pick, but my bet is that they will not really start true bulk manufacturing until gen 3 products.
Surface Phone sounds interesting... but I think that Nokia has such a monumental following for the WP platform that this will probably be their hardest sell out of anything. Nokia has some 70+% of the WP market, and they were late to join the WP bandwagon... that is some serious work on their part. Still, I will be curious to see if they come up with something that is better than my 920... it is one sweet phone!
At this point I will be very surprised if the NextBox does not get introduced as the Surface PC. Make it a closed system box with win8 that can do both the social/causal and hard core games, and then release Office for it, and bring the entire Windows Store to it. Then, take Xbox, and completely turn it into a distribution platform (like steam) rather than a piece of hardware. Instantly you have access to a huge market of computers more than capable of gaming which can tap into the service, and MS will get a cut of every game sold for both consoles and PC. Just be sure to have good sales from time to time to keep Steam users (like myself) happy.
You want to make a closed ecosystem work? That is how you do it: Make an ecosystem where lots of people can bring their products in and sell them. Make solid hardware that becomes the standard, but do not close out other hardware vendors. Make good standard software for web browsing, searching, email, and multimedia viewing, but do not prevent software developers from making their own stuff which may be better. Make a closed app ecosystem, but do it in a way that makes viruses and malware a thing of the past, and where software developers can keep more of their money than on other platforms. In other words, make a complete package, but still make it profitable for others to come in and do their thing. Don't become Apple who alienates everyone, but also do not become Android which is so open that is lacks coherence. MS is shooting for that middle ground, and while I am not convinced MS will succeed at this, but I am more than happy to see them moving in this direction.