Hopefully the backlog clears up in the next 18 months, I've been running my gear for about as long as possible. I have switches that just hit 10 years of service last month(still under vendor support). My load balancers (Citrix, not F5) go EOL in Jan 2024, so hopefully in 18 months I can easily replace them that will mean they have had ~9 years of service(with 3 SSD failures across different units over that time, I guess the SSD quality Citrix uses is not great, most recently I had SSDs in both units in a pair start to fail, took 6 months to figure it out. Units would fail back and forth between each other every few weeks, support couldn't figure out the problem and blamed my network, eventually I saw the kernel messages showing the disk errors).
My primary flash storage array is in it's 7th year of service 0 hardware or software failures(other arrays are a bit more recent and have suffered a HD failure here and there, one had a memory chip go bad a couple years ago). Many servers are 6+ years old still running fine. Not planning on major server or storage changes before 2024. But the load balancers need to stay on vendor support, since they are fairly exposed. If not for end of life I would probably run the Netscalers far past next year as they have plenty of capacity averaging under 10% utilization on what was considered a low end unit in 2014(was their lowest cost unit that had dual power supplies).
I used F5 for nearly a decade, liked them a lot but when I last moved jobs decided to try Citrix, had heard good things but had no prior experience with them, now I have 10 years of experience(at the same company) and I like them, still like F5 too, lots of fond memories.