But how quickly though? Do we know the write endurance of the Mac SSDs?
I'm not a Mac fanboy by any means. But SSD write endurance has become ridiculous. Even on a cheap-ish read-intensive server-class 1 TB NVMe SSD (~$300) you get around 1 petabyte total write endurance, meaning you can write essentially the entire contents of the disk every day for 5 years and still be within the warranty. That is orders of magnitude beyond what any consumer is going to subject their disk to.
There is always a possibility that a part of the computer will fail. But if the SSD is less likely to fail than any other random IC on the motherboard, having it soldered on doesn't factor significantly into the failure statistics.
Of course it's super annoying that you can't upgrade the disk size, but that's another point.
I've got two Macbook Pros - a 2014 15" (500 GB SSD) and a 2015 13" (1 TB SSD). Both are still going. I can't imagine newer Macs are worse. I'd be more concerned about replacing the battery!
The newer ones could be worse as they move to smaller process nodes and store more bits per cell. That said, the controller logic is improving, and larger capacities mean more room for wear leveling, so it shouldn't be too bad.
My MacBook Pro (2015, 15 inch) started having some SSD issues earlier this year after a bit more than seven years of heavy use, but it does seem to be partially mechanical because it would mostly happen after it had been in my bag.
Since I bought an M2 Pro to replace it, it hasn’t had the issue I think because I’m just leaving it at home and not flexing or squeezing it much. Perhaps the issue could be fixed permanently and properly with a bit of hot air to re-flow the solder balls.
That's not even that bad if you have a hot air gun and a reball kit. What's worse is the flash chips having some kind of cryptographic identifier that locks them to the machine, so you couldn't replace the flash if you wanted to.
The Mac Pro missing RAM slots was disappointing to me. Performance uber alles and all that, but upgradability has benefits as well. Until Apple started soldering RAM, I always did aftermarket RAM upgrades, and even recently doubled the RAM on a 12 year-old file server.
They would need to extend the slots from the existing ram, which would slow it down even when empty, or they would need to use up a lot of silicon adding more memory channels. It really does make sense to solder on RAM for best performance. Though alternative sockets like CAMM might help in the future.
But you can't do a trade-in, the RAM they sell is extremely overpriced, and as mentioned elsewhere there's no excuse for the SSD.