Not forget to mention, there is sentimental values and nostalgia vibe for older devices, the exiting of 2G, 3G and future 4G networks is really not a good news to me at all.
i think likely 4G is still going to stay for quite a while.
Achieving the same indoor coverage with 5G as 4G is significantly more difficult, often requiring 10 to 100 times more infrastructure density, depending on the frequency band used.
4G first launch in 2012, and it takes all the way until 2020 for 4G to be well-established as the primary, highly stable network across Singapore, with availability often exceeding 90–95%.
you can imagine how long will it take for 5G to fully cover indoor before they can eliminate 4G.
not only they need significantly more cell towers to cover than 4G due to the frequency band used by 5G but also it costs more to implement 5G than 4G as well.