First sentence on the first hit when searching for “Gmail smtp imap”:
For non-Gmail clients, Gmail supports the standard IMAP, POP, and SMTP protocols.
https://developers.google.com/gmail/imap/imap-smtp
What you’re referring to is the fact that GMail has apparently disabled authentication using username + password for SMTP/IMAP. I would assume that application passwords still work fine as a workaround, even if they don’t mention it specifically.
As far as I know the 1DXIII is still being produced, nearly 4 and a half years after its launch.
Single lens reflexes have one massive advantage: the sensor is not being used while you’re composing or idle, which means the sensor doesn’t heat up as much. Hot sensors generate noise, which you then have to compensate for (by doing an equal exposure with the shutter closed to remove the hot pixels).
But mirrorless is faster, cheaper to produce, smaller. It’s inevitable that DSLRs will soon be a relic of the past. But they won’t be for a while: 30% of the enthusiast market in 2022 was still DSLRs.