Yes, it's getting bad. I bought my last furnace/evaporator/condensor unit online from a website run by a location of one of the largest HVAC distributors in the US. I looked back at their website a year ago, it now has an "under construction" message on it, that never changes. I think they shut it down quietly, probably from contractor pressure.
I went to get a replacement overhead garage door bottom seal from the local company that I had originally install the door many years ago. I had gone and bought a replacement torsion spring from them years later when one of the two broke. Installed it safely myself, no big deal. But when I went there to get the seal, the parts counter was gone, that door just lead into their break room. A guy came out of an office and asked if he could help me, wondering what I was doing there. I explained what I needed, and what happened to the counter? He explained to me that due to lawsuits, they no longer sold parts anymore. However, since I only needed a seal, and was unlikely to try to hang or strangle myself with it, he sort of looked the other way and had somebody get me one. If I needed another spring, he would not have done it. And the torsion springs have also disappeared from the big home supply retailers.
Locally, HVAC parts have pretty much disappeared retail. The supply companies are wholesale only now, and they require a state AC license to open an account (thinly veiled unionism). They won't sell you anything, not even a blower motor or motor start capacitor.
I salvaged contactors, caps, and one of the condensor fan motors from my old units. So if there is a failure on a July night, I might have a part I can use to get one running again. I also salvaged the old 24 volt control transformer boxes, and I have used one of those to troubleshoot our sprinkler system after a lightning strike. The valve solenoids are 24 VAC.
Parts for just about anything are available online somewhere, but it takes a lot of looking. It took me 3 days to find a replacement 240 VAC timer motor with the correct gearing and output shaft on it for a pool pump timer. Then 3-4 days for it to arrive.
-- Telly, the D-I-Y guy --
Two fools dancing on the hands of time