Will changing from Uverse copper to Uverse fibre change my set top boxes

You'll be fine.

However, if you decide to run cat-6 Ethernet out of your gateway to your DVR or receivers, you may have to change gateways. The only cost associated there was me buying the Ethernet cable.

If you want the benefit of more simultaneous streams (up from 4 to 6) due to the fiber connection, then you may need a newer DVR (if your older one doesn't support 6 streams).

Yeah. When I went from Internet 100 to Internet 1000, it opened the door to six streams. Since I only have one additional TV and very rarely record three shows at a time, I felt no need to lose my saved shows in a DVR swap.

Internet 300 and Internet 500 are also fiber connections. These don't include the six stream DVR, although you *might* be able to con your way into one...it's probably not recommended since U-Verse TV takes away from internet bandwidth. If you have Internet 300 or 500 and are using more than four streams of TV, you could run into issues.

@ClarkTE4 , one thing I neglected to mention:  If any of your TV Receivers are connected via Coax, this could create some issues because the newer Gateways don't have coax connectors.  I think this is why @baseballisback said:

if you decide to run cat-6 Ethernet out of your gateway to your DVR or receivers, you may have to change gateways

although I think he said it backwards.

If you're already Ethernet-connected, no issue whatever.  If you can switch to Ethernet-connected, then you'll be fine.

I was having problems with the "on demand" portion of my DVR. I was sent a new gateway. It didn't have the coax output. I then put Ethernet from the gateway to the DVR.

I've still got the original IPN4320 that was installed in 2009.

There's not a single receiver which is black and wired? Maybe it's a good thing they're trying to get everyone on wireless if the only sites are the VIP 1200.