Worthwhile replacing battery of 1st generation iPhone SE? I am considering replacing the battery in my iPhone SE. It drops from 70% charge at room temperature to 10% charge in the outdoor winter cold, then shuts off, leaving me stranded without connectivity.
When I bought the phone several years ago, there was a high profile problem where iOS upgrades would slow the clocks on older phones to make up for the short battery life.  Due to public outcry, Apple agreed to replace the battery for free.  Since I don't use the phone much, I didn't take advantage of that offer initially, and when I decided to, it was too late.
If I replace the battery now, it would likely cost under $100, including tax (about 12% here).  It is a 1st generation iPhone SE [1], however, and I'm not sure how able it will be to host many more iOS upgrades.  At some point, Apple will not allow upgrades in order to avoid untenable customer experiences.
For those who have visibility into the technology trend, how likely is it that in the next year, the growing procesing/memory demands of iOS upgrades will make them unsupportable by 1st generation iPhone SEs?
I hardly use the phone (not allowed to have one at work, don't need it at home), so the $150/year of amortized phone cost seems...OK, I suppose.  When I need it, however, I really need it, e.g., navigating a new city, looking up things or communicating when doing milk run activities.
I suppose that it's not the end of the world to be stuck without iOS upgrades, but I anticipate running into problems with web apps and webpage compatibility, as well as stale security.
[1] Model MP822VC/A
Generally, Apple supports iPhones for seven years—so going from the date it was discontinued in 2018, would give a window of support until 2025. Sometimes, due to specific hardware being able to run later versions of iOS, it may be possible to go beyond that point, but is a gamble.
If you're looking at extending the value, the $100 cost looks like a good deal—as long as you don't need the latest-and-greatest. Keep in mind, though, that the proliferation of 5G networks and changing carrier support may factor into your decision.