"With Boston, the ARM-based solution (1535 servers; 1.6 racks; 2 switches; its power consumption at 13kW) can offer 40 percent lower total cost of ownership, while it can be implemented in 61 percent less space, he claimed, compared to the X86-based solution (1997 servers; 4 racks; 44 switches;37kW)."
Effectively, the statement implies less space and less power consumption per server compared ARM to x86. I don't quite understand the difference of number of switches - 2 vs 44.
There is a movement of 64 bits ARM server. Whether it will take over x86 based server, only time can tell. Cloud based service providers may be able to shorten the time if the risk is properly handled.