Developing world mostly wireless
The developing world lags on wired broadband as most of the growth there is with wireless Internet. The end user hardware is mostly cellphones, which is multifunction and cheaper than PCs. And the infrastructure costs to rollout cell towers is cheaper than running cable to every hut.
"If you want to anger a conservative lie to him.
If you want to anger a liberal tell him the truth."
End of DSL
If FTTH is not what you provide copper DSL in the developing world would be a joke. In most of those countries the POTS lines barely work. I don't know what level 2G, 3G, 4G or LTE but the cell system is cheaper and more reliable.
Slow DSL is being killed off in the US. I think at&t and Verizon are moving to cell LTE internet service if Uverse or FTTH is not already in place. If it was not for the caps and high cost LTE would be a better deal for speed then old 3 or 6 meg DSL.
DSL subs specifically declining?
Granted, it's a decline, but it's only a decline of .08% and more than half of the fixed internet service is still provided by DSL. Add in VDSL service offerings and xDSL clearly had a foothold around the world.