ARM managed to take the entire mobile market because those low power consumption ARM SoCs are everywhere, you can buy a tiny ARM board running Linux for $50 or less and there are thousands of sellers on ebay.com/taobao.com. However, it is a completely different situation when it comes to ARM for data centres - it is damn hard to find any 64bit ARM platform that allow you have say 32GBytes RAM and a few PCIE slots at reasonable price (e.g. comparable to Xeons). Not talking about cloud, I want 3 such ARM machines sitting in my home lab working 24/7 at 100% load for me and I need to play on the hardware side a little bit (e.g. try different SSDs).