To reduce costs and hassles I decided to try Apple's T3/USB-C to T2 adapter. It costs around $45. Everything works for now -- except my external HDMI monitor. It flickers on and off. I might play with it a bit but for now I have it connected directly to the laptop via a compact Anker USB-C hub . Apple tells us that "This adapter does not support DisplayPort displays...". I wonder if the HDMI display connected to a Hub with a DisplayPort/T2 cables affected by this limitation.
Overall it's worth the money, even though I'm likely to switch everything to a USB-C or better hub eventually. The single remaining Firewire 800 device can be retired.
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 When I disconnect the laptop I have to pull two cables! Oldness helps with the indignity.