As faster Wi-Fi speeds seep into the enterprise space, I'm willing to bet the corporate LAN supporting all that new wireless kit will need a corresponding speed boost for faster overall throughput. How fast is an interesting question and I'm not sure there's a right answer other than "As fast as possible and affordable."
I have a love/hate relationship with Wi-Fi. The 2.4 Ghz band has given us "free" and low-cost roaming Internet access around the globe. Your cell phone may not work from country to country or region to region, but you can almost always count on finding at least an 802.11b or g signal anywhere you go. Moving upband, 802.11a in 5 GHz provides faster speeds with the trade-off of shorter distances.
Today, 802.11n with data rates from 54 Mbps up to 600 Mbps -- depending on antennas and distance -- is being supplanted by 802.11ac "5G" and a potential of a whopping 1.3 GBps on a perfect day and setup. You may "only" get 800 Mbps out of an 802.11ac router, but that's still a lot better than maxing out at 450 to 600 Mbps.
If that's not fast enough, WiGig (802.11ad) will push in-room wireless speeds up to 5 Gbps within the enterprise using 60 GHz frequencies. In early November, Cisco invested money in 60 GHz WiGIg chipmaker Wilocity to develop enterprise networking products. The 60 GHz band will become more important as mobile device manufacturers roll it into phones, tablets, and laptops for both "wireless docking stations" and its ability to perform high-speed data transfers. Imagine being able to perform a rapid "sync" between a mobile device and corporate servers for backup/archiving purposes without cluttering 2.4 GHz or 5 GHz speeds.
With a deployment of anything up to 802.11n, you could probably get away with the supporting wired network to be Gigabit Ethernet or even 100 Mbps, depending on budget, how many users you were putting on a network segment, expected wireless usage and whether or not it was the accounting department or the executive suite -- (The latter typically requesting the highest speeds available because C-levels just don't want to wait).
The combination of 5G and WiGig changes all that. The "floor" for network speeds starts at GigE and teeters on 10 GigE, depending on the allowances you want to make for supporting in-building WiGig devices. Since WiGig, by its nature, is a high-speed data transfer mechanism, a lot of WiGig devices conducting data sync/backup operations will need door-to-door 10 Gbps (or faster) routes to the server room.
WAN connectivity may require a second look down the road as well, depending upon the quality of service and speeds you wish to support outside the corporate office. Cellular data speeds are on the increase with the worldwide rollout of LTE. Sprint has touted potential speeds of 1 to 2 Gbps (ultimately, eventually, when the tide is high and nobody else around) once it finishes up a bunch of next generation upgrades.
In more today-now real world condition, independent testing shows AT&T is to provide an average of nearly 19 Mbps download speeds with 9 Mbps uploads. Verizon isn't far behind with around 14 Mbps down and 8.5 Mbps upward. Given the LTE arms race of speed, these numbers will continue upward to place increasing need for more responsive links between the corporate network and remote workers.
Trying to figure out a ballpark impact of remote devices on Internet connectivity will be a challenging task for some organizations. It is easy to model a known number of mobile workers using business supplied devices, but throw in BYOD and suddenly you get into a world of statistical estimates based upon carriers and age of devices. Surge events such as trade shows will throw spikes into off-site traffic with the "Killer surge" associated with the annual customer/partner conference.
Off-site connectivity's saving grace of sorts is that the need for more speed should be -- with the exception of the annual all-hands conference -- a gradual rise in traffic. Short of a sudden switch out of corporate-swapped devices -- say migrating the whole company from 3G data services to AT&T LTE devices overnight -- phones, tablets and WiFi hotspots will be upgraded on a gradual basis over time.