Dear MS, I want a 4G LTE Surface tablet.
They can add it to the RT or the Pro, as long as they subsidize the price. Skip the WiMax radio, it's been done and it's going away.
The only thing Surface is lacking right now as far as completely wiping out the iPad is a cellular data option. This is a huge factor in enterprise adoption. I don't see a lot of mobile employees (think cable guy, DSL installation guy, etc.) that already use 3G/4G iPads making the switch to Surface if they have to carry around a WiFi hotspot or pay for hotspot privileges on their company phones for on-site data access. The more you can claim "all-in-one solution" the more the higher-ups will buy into Surface for enterprise.