Not sure I follow, isn't the reason you are excited about fibre that it implies a good connection to the "backbone". Compared to DSL, cable or wireless which are is really limiting even in the 50mbit range (in practice).
And for the distances we talk about you kind of get fibre anyway since it makes the most sense. But many do have a copper connection to their fibre, just the last stetch.
I was just making a commentary on the traps some of our end-customers fall into, when they upgrade the connection to fiber thinking it will improve their network speeds when the protocol is in fact the limiting factor.
Of course; telecoms are always pushing the leading edge of data transfer would need fiber for 10/25/40/50/100/400GbE. Some of our customers are still making designs using Triple Speed 10/100/1000Mbps though. For embedded use cases that's good enough, but they still often needlessly spend more on fiber cables, regardless of necessity.
Fiber is very cheap. Easily cheaper than good copper cable if you're aiming for 10 Gbps or later.
The hardware less so, but even then very much affordable.
If you're planning for the long term and think that running new cabling everywhere would be a huge pain, or there's some sort of concern with interference, I would definitely go with fiber.
I'd love to agree, but there's a whole list of companies I can name and shame where upgrading was, and is, simply a waste of time and resources for everyone involved in the design. It'll do the same speed regardless, with identical error rates, because the protocol hasn't changed. It's simply marketing guff that they can slap on the same product. The "gold-plated HDMI" scam with a fake mustache.
I think you've just got some specific situation that's not quite obvious from your comments. It's not at all clear what's being upgraded, what kind of equipment is involved, and why you can predict the effort will be useless.
End users traverse the same core equipment no matter what the last mile cable media is. Newer fiber builds may have more efficient core gear or have more capacity but this is all limited by the ratio of users served by a particular backhaul link, and also the topology and configurations made by the operator. Large networks are a challenge for some.
Fiber is a lot less susceptible to water intrusion but still has the same potential for outages due to cable damage along roadsides and on aerial poles with power lines.
And for the distances we talk about you kind of get fibre anyway since it makes the most sense. But many do have a copper connection to their fibre, just the last stetch.