Requiring users to install another browser like Mist, is too much of a barrier for any kind of mainstream adoption.
What are potential solutions and how close are they in actual practicality?
One solution is to use browser plugins like Metamask that acts as a gateway to a public node, along with client-side key management and transaction signing.
Once light clients are available, browser plugins could possibly be even more secure.
You can simply access DApps with your regular browser (crhome, firefox) as long as you have a working ethereum node running which allows rpc cors requests.
If they dont want to run an ethereum node on their machine, you are probably not understanding the benefits of decentralization. But yeah, that's maybe why we need light clients.
In Microsoft Azure it's already possible to install a node with one click. I dont know why this should not be available for other environments soon, too?