Funny, I can't find a firmware upgrade for a single one of the routers I have (or have deployed) in the last 10 years. 95% of those units are still in service. Or, wait...are you advocating that myself and all of my clients rush out to replace perfectly functional equipment? Why? Why would you advocate that? Do you believe that IPv6 is somehow a Good Thing? Why?
What are the negatives of IPv6:
Network renumbering each time you switch ISPs. A real problem for consumers who actually care about their networks and change providers periodically to avoid getting raped by the local monopolies. It's also a massive pain for SMBs who change ISPs for the same reasons, but also tend to move more often. Their networks are larger than consumers and have even more reason to want to static address items on the network. Shockingly, you'll find that there are individuals out there who want control over their network that doesn't rely on DNS or other "dynamic" technologies which don't quite as well as advertised.
No multihoming or failover. Oh, you can multi-home or failover if you happen to have a router that speaks BGP and an ISP willing to provide the service. Most consumers and SMBs don't have such options. failover would mean renumbering the entire network. Multihoming is pretty much right out.
No host obfuscation; no privacy. NAT isn't security and certainly if you try hard enough you can profile networks through NAT. Still, even half-assed NATs of today (such as OpenWRT on a Netgear WNDR7200V2) can be easily configured to obfuscate the individual computers requesting resources enough that you would have to be a top 1% security researcher to profile the damned things. IPv6 tags each device with it's own external IP; every single thing that device does is traceable directly to it. IPv6 means privacy is finally and completely dead.
One simple mistake lets the internet attack your toaster. Stateful firewalls as are required to protect people using IPv6 from having the outside world directly address their device are complicated. Far more so than the simple NAT+Firewall devices of yore. They require more knowledge to operate and maintain if you are an individual of the belief that the internet should not be allowed to attack your toaster for fun. Firewalls on network edge devices are not remotely simple enough or powerful enough to properly replace NAT yet.
What are the benefits of IPv6
It makes the lives of programmers easier. Yes; programmers, those great big whiny babies of the world will finally be able to leave behind the programming techniques we've spent the past 15 years perfecting. They can assume that devices can speak to one another with nothing in between them (which isn't true, because a proper consumer firewall won't allow the internet to talk to your toaster, even in IPv6, but hey, let's keep beating the end-to-end drum, eh?) The end-to-end model makes life a small (probably single digit, given the libraries that exist for NAT traversal by now) bit easier. This minor convenience for the elite few, the developers, the worthy is worth making the lives of IT operations more difficult and telling the entire world they must buy new devices, even though no new devices exist which are actually ready to do the task in a simple, cheap and simultaneously secure fashion. Even if the devices did exist, you're asking the whole world to replace perfectly working equipment in order to benefit the whiny few.
We're going to run out of IPv4 addresses. Yep. This is a problem. Artificial scarcity is a bitch, ain't it? Fortunately, we can all break the rules when are forced to switch and simply implement NAT66 and keep all our shit working. I even get to listen to developers howl. It's awesome.
Break the rules
Well let me be the first to say: fuck those whiny bitches. If their applications from the whiny bitch department don't work, I'll get one from another developer that does. My network, my rules. I give zero fucks about making the lives of developers easier. You don't get to talk to my toaster, or my lightbulb, my furnace of my server unless I bloody say so. And no, I won't pay Cisco rates for the privilege of making the lives of some whiny bitch developers easier.
Either the upgrade provides me as a consumer and systems administrator with a return on investment or you can go straight to hell. In 15 years, when my routers die, I'll send them down there do join you. When I do replace them, they'll use NAT66 (available on things like pfsense) so that I can get the features that are of use to me. Until then, cheers mate.