I guess people who don't have a smartphone have good reasons for that: either they don't want one or they don't feel the need to have one. Not much can be done in the former case, but in the latter, giving them a taste of the kind of service they could expect on a smartphone could be a good idea. Your web-browser knows your location, it has access to your mail, calendar, etc just like your mobile. Assuming you use the same google profile at home and at work, it can even somewhat know your habbits. Sure, it won't give you instant information such as "get out of that bus now, there's traffic jam ahead" (does it do that on a mobile?). But info such as "you have a flight in 2h, you should leave now" or "this is XXX's birthday, leave a note" is perfectly available and useful on a desktop.
I read that google now was supposed to be a showcase of what google's information collection could do for us. Google collects information from everybody, no matter if they use a desktop and/or a mobile... Why should the service be restricted to mobile owners then?