Get a server or some hosting, load it with whatever you need - mail, web, cloudy things, media, communications etc - and use a portable terminal to access it when on the move. That portable terminal can be a phone with a browser or some future device which is more tailored to this type of application. With the current generation of SoC, Wasm and a capable browser (Firefox Nightly Preview is shaping up nicely) this setup is a viable replacement for most 'apps'. One of the advantages of such a setup is that those 'apps' do no get to track your every move - that is, as long as that capability is not built into the browser at some stage (persistent web workers etc).