Ok, call me stupid or ignorant, but here goes...
Given the recent announcements and details surrounding Windows Azure, cloud services (.NET, SQL, etc.), the increased use of PKI for tying together internal and external assets within a homogenous management realm, heterogenious identity management, and the water-testing efforts of AIS, MDOP, Office Live Workspaces, Hosted Exchange services, and Live Mesh, I think we're going to see a gradual shift towards a two-sector approach to infrastructure or desktop "management": Host-Managed or Self-Managed.
Today we have a choice of the small business approach using System Center Essentials (SCE) or the larger enterprise collective of System Center products (Configuration Manager, Data Protection Manager, Operations Manager, etc.). Sort of paralleled with the aims of Small Business Server against Windows Server product lines. Basically: Bundled "Lite" or Separate "Full" versions.
For smaller businesses (those with less than 500 users is my guess) Microsoft may provide hosted "managed" services to replace the need for SCE inside a customer environment. The benefits are obvious and tangible: Reduced overhead costs, reduced labor costs, reduced downtime from diverted labor for troubleshooting (your admin person can continue working on other things instead of stopping to diagnose SCE problems). No dedicated servers or rack space. No increase to electrical or cooling costs. Just deploy an agent to your desktops and log into your web console to do your management work.
Quite a few consulting partners and service providers offer managed services to their customers. Even our local cable company (Cox) offers it now. Remote management and helpdesk support by VPN. For many customers this has worked out very well. Many more haven't been exposed to this yet or are stuck in their current investment and can't justify a change as drastic as this. So there's a market out there still to be tapped for this.
Obviously you could apply arguments against this concept, much like "cloud services" in general. Most hinge on availability or "uptime". But unless you're dealing with a small business operating in a nightmarish IT environment, the level of support won't be second-by-second. Probably not even hour by hour. For the crisis situation, maybe there could be a staged approach with an internal server acting as backup, who knows. That could be an added option.
The possibilities are there already. I'm sure Microsoft is already working on this, at least in a prototype or proof-of-concept mode. Here's how I would imagine it:
Small business customer has 250 employees with computers. Maybe a handful of dedicated physical servers, running SBS+Exchange, another File/Print, another line-of-business box, and maybe some others. Now you want to get a better handle on patching and health checkups and maybe controlling desktop settings and installing software. You could look at WSUS and SCE and trying to package with Wise and deploying with Group Policy (yuck!), or scale up (and more costly) to System Center Configuration Manager + WSUS. OR... You could sign up for (hypothetically now, don't freak out on me...) subscribe to a service by Microsoft that bundles Software Assurance (subscription upgrades) with MDOP and maybe a System Center Live Essentials service, and use App-V to package your apps and deploy them that way.
Just hypothetical of course. The current versions of these products would need some adjustments to fit into a small business environment, but it's entirely possible.
So you'd have to options: For enterprise customers, you'd still have the A La Carte choices, and for the smaller customers they could buy into the toaster-oven concept. A simple to implement and easy to administer service without the need to buy hardware or maintain the management app itself (ever spent hours troubleshooting SMS issues? not very fun). I have no inside information on any of this, so this is all speculation on my part alone. I could see it though.