We still run W8.1 on new machines we purchase (the odd laptop) as we exercise our downgrade rights. As for the bulk of our machines, they are very old OptiPlex 760s and 780's - 3GHz core 2 duos with 4GB RAM. They were given a facelift 18 months ago with 120GB SSDs (£45 per unit, Kingston). This has pretty much negated the need for any machines to be purchased, a chunk are over 5 years old and still going strong. Spares are plentiful and I can buy refurbished to plug any failure gaps.
There is simply no need to upgrade our machines (short of catastrophic losses). Sure it can be seen as storing problems for the future (they will die some time) but when budgets were slashed it was easier for me to repair and upgrade what we have - SSDs were a godsend (a dual core 3GHz is more than enough for internet/office/lightweight picture and video editing). Only our autocad suite were upgraded properly (even those only got refurbished i5s and cheap GFX cards)