The seems to be a growing array of parts in short supply. Some basics like a Chassis are readily available and X570 motherboards are widely available.
The new (2019) Corsair RM power supplies range from 650W to 850W which is fine for 95% of users and the availability seems to be good. The more expensive (2019) Corsair AX series are available in 850W and 1000W. The older HXi and AXi are available in higher capacity but supplies are limited. The RM650 has been used for refurbishing the SPEC-01 which was using an old obsolete PSU.
The shortage of NVIDIA graphics cards has been of real concern. Radeon cards are better supplied but new cards are upcoming. NVIDIA has said stocks of Ampere are going to be short heading into 2021 and eventually they will provide cards to those who want them.
CPU availability has been all over the dial depending on sales. Ryzen 3000 series are slowly going to be replaced with Ryzen 5000 processors. For Intel users Rocket Lake is now expected in Q1 2021.
Given the component situation, the appetite for an overhaul is not on the radar. Next year AMD is expected to move to DDR5 which probably will enter the market in Q3.
Depending on the needs, an incremental upgrade will be more cost effective and wait for DDR5 to do a forklift upgrade.
Lots of component deals are common on Black Friday. This year the discounting will likely be very favorable.
SSD prices have fallen considerably so upgrades will be very affordable. hard disks are popular for media libraries and capacity upgrades are very affordable.
A better monitor is another option. Many have low cost panels, now with lower prices a better quality screen is much more affordable.