There are places for 'cloud services', like mozy, gotomypc etc.
Mozy reason for existing is physically storing your data in a redundant place, which the cloud does better hands down.
Certain apps really make sense to be very mobile. For traveling salesforces, CRM does, for email etc.
But lets just talk ERP. How many of us are doing production entry, or purchase orders while standing on line at Costco?? I would guess that 95% of all ERP functions are done perfectly well sitting at a 24"" monitor on a desk at a fixed location/plant. And the few places where mobility makes sense such as WMS, is perfectly handled via local networks, not trying to integrate a cloud service, back through a firewall to local device and bang out hundreds of orders an hour without waiting for internet and browser latency.
The only way to start talking about doing away with on-premise IT costs is if you move EVERYTHING to the cloud, which means its not likely a pure saas solution will work because good luck integrating netsuite with your scores of other applications, including Office, CAD, email, file sharing, search etc. Sure they claim to do some of this but in most cases their UI is way to slow compared to using outlook or autocad on the desktop.
The other option is you essentially (in a virtual sense) ""ship"" all your servers to an I-BN or rackspace and they run ALL of your applications there and you use VDI (Virtual Desktop Interface) or terminal servers.
However, take a look at the cost for a 100% full service solution where they offer everything, including phone support, network support, application support, full image based backups with real time disaster recovery (shameless plug:
http://www.eversafe-backup.com ), helping end users when they can't print a document, email server (with exchange like flexibility) etc.
Based on what I've seen quoted by the likes of Rackspace, you'll fall off your chair. And that still doesn't handle the issue when your local firewall has problem, your internet goes down, your cable modem has a problem, a local printer has an issue etc. And that also assumes you throw away all PC's and go with Winterm's or something similar (which are no longer any cheaper than laptops & desktops).
And when you go this route, except for laptops, mobile devices suck because a citrix/terminal server interface is only viable for emergency use on a tablet.
And yes, there is windows licensing, cal's, etc, it's just all embedded in the service price and trust me, they are marking it up way more than the average 10% most IT var's do.
If you decide to do away with all things windows and go completely saas, good luck connecting 5-8 saas providers into a unified solution that works for your business, doesn't have you flipping between multiple 'apps' on your tablet, or browsers etc. And then you probably need devices like desktops for local storage to exchange files.
IMHO, other than certain niche applications, its a solution created by an industry looking to come up with an excuse as to why people can't remain comfortable with their current IT and spend money again like they did with the windows wave in the 90's. And a solution that doesn't require selling customers every year on why they need to pay annual maintenance. A solution that gets them to rebuy your product every 3 years.
And the only way saas makes sense is multi-tenent which means far less customizability and flexibility which will inevitably lead to alot of local Excel workarounds and thus local servers and desktop computing.
All the reasons we moved away from Timeshare computing in the 70's to Desktop computing in the 80's. Man peoples memories are short