Microsoft is still pushing Bing, and I think Yahoo exists; and both of those providers also provide free email services (some under different brand names).
Apple competes on entire phone platforms, and Android as an operating system for phones is provided free to enable a market place across several different manufacturer's devices; that is likely what's saving //Apple// as a monopoly for mobiles.
Amazon for shopping... the Whole Foods horizontal integration may be problematic. I think it depends on how different platforms and services are broken up. It would probably be OK with the correct kind of regulation to ensure that it isn't used as an unfair competitive advantage. In that respect I think Walmart might also have issues.
What I think might improve things is more consumer protections, particularly in the form of requiring reasonable cost access to paid support (even for products that are otherwise free). We've heard of users being locked out of their contact address and account data far too often, even for paying or previously paying users.