For non-technical folks, I think a low end, high capacity HDD + Optane will be more practical than low capacity SSDs, especially in laptops.
The problem comes down to cost. That 16GB Optane cache costs around $33 (at least for consumer pricing). Add to that the cost of the 1TB drive, and you're looking at spending close to $80 for that partially-cached 1TB hard drive with unpredictable performance. Sure, the laptop manufacturer probably gets better bulk pricing on these things, but some 500GB SSDs can be had for as little as $50 now, and would provide better performance overall, along with superior impact resistance and reduced power use, which are worth considering for a laptop. Or, for one who needs the capacity for bulk storage, keep the hard drive in the system, but add a 250GB boot SSD for about the same cost, providing better performance for everything installed to the SSD, and 25% more storage in total, albeit with the need to sort things between two drives. Or, to avoid that, just go the 1TB SSD route, which start at around $100, which is somewhat more, but again, provides better overall performance. It probably won't be long before even that price difference evaporates though.
SSD prices have been dropping recently, while the price of Optane has largely stagnated, making the value less attractive than when these cache drives first came out. Over the last two years, the prices of these Optane drives have only dropped by 20-25%, while the prices of SSDs have dropped by around 65-70%. While a 16GB optane cache may have been priced similar to a 120GB SSD then, you can now get an SSD with double that capacity for the same price. And when you figure in the cost of a 1TB hard drive, which have also stagnated, the pricing of SSDs becomes even more favorable.
What's wrong with just installing a few that you play at a time?
Another option would be to send those extra games over to the hard drive when not being played, and then back to the SSD when you start playing them again. Steam includes the option to move games between libraries on different drives, and doing that should be quicker than re-downloading. Or just play them from the hard drive if load times aren't too bad. If it's a game that's not played often, the files are likely to not be in the Optane cache anyway, especially for the lower-capacity units.
And while the article compares the 118GB Optane 800p for $175 against a 512GB 970 Pro for $160, an even better comparison would be against the cheaper, higher capacity SSDs, like Intel's own 1TB 660p NVME drive for just $115. As far as game load times are concerned, anything faster than that will make an imperceptable difference, so when you can get double the capacity for around 30% less than a 970 Pro, that option makes a lot more sense.