The router will be great, you'll have to upgrade the modem long before you have to deal with the router.
As for the modem, that's probably the bare minimum I'd get to be confirmable saying it'd work for 2 people. I can't find Comcast's compatibility list in a quick glance, but Cox supports that modem on plans up to 250 Mbps - this will likely support you staying in the lowest tier for quite a while.
Faster speeds than that are only really useful for the impatient, who don't want to wait for big downloads (like new games/updates), or for big families who do a ton of streaming. If you're not anticipating either of those in the next 5 years, the $50 spent on that modem will not be lost.