The problem is that smartphone batteries aren't standardized and eventually Samsung will stop producing them.

At some point the cost of a newer phone is less than the incremental value over the existing phone.

Only if the newer phone actually has desirable features.

- physical, normal headphone port

- Swappable battery

- microsd card slot

- 1st class LineageOS support

I think Samsung Galaxy S5 is the newest phone that has all four of the features, with irblaster and waterproofing as nice extras.

That's kind of the point. Isn't there some advantage in supporting a venture that could ultimately produce an affordable new phone with all of those things?

At some point the existing stock of phones with the features you want is going to wear out unless somebody makes some new ones.

Sure. But the Librem 5 (USA) isn't that phone. Maybe the Pine Phone (or similar) could be.