There are articles floating around the topic of SHA-1 deprecation. The gist of it is that in (mostly) developing countries, people are still using mobile/computing devices that are 5 years old (or older) and do not support SHA-2. As a consequence, the deprecation of SHA-1 would result in their being "cut off from the Internet as we know it."
Yeah, there are many problems with this oversimplification, but here's some questions:
There are estimates that it would cost something in the ballpark of several hundred thousand US dollars to create a SHA-1 collision. But how much time does that take?
Depending on the answer to the first question, why not extend client and CA support for SHA-1, provided that certificate validity periods are simply shortened to 6 months? 3 months? One? This seems especially more feasible with the kind of automation LetsEncrypt offers.
In my view, there's nothing wrong with the SHA-1 algorithm. No one has "broken" or is coming close to "breaking" the algorithm per se. It is just becoming computationally more feasible to overcome its cryptographic strength over the typical course of a certificate's validity period. So long as that's the case, although it may be no longer well suited for year-long (or multi-year) certificate validity periods, it's still technically safe to use in more limited applications. After all... all forms of encryption are about time, not about impenetrability.
Would this proposal sufficiently eliminate known risks to make SHA-1 safe to use on older devices?