Yeah in your dreams maybe. I'm often seeing zero bars, asking others if they have any signal only to have them show me a full 5G signal. New towers aren't backwards compatible, and the bandwidth has been largely reduced.
Yup.
In tech-speak there is 5G NSA (Non-Standalone Architecture) and 5G SA (Standalone Architecture).
5G NSA is a kludge, it is 5G radios operating on a legacy 4G core. Inherently backwards compatible.
5G SA is 5G radios on 5G core. Clearly not backwards compatible.
5G SA is the preferred route for good reason:
1. It delivers reduced power consumption at both operator and user-device level
2. It delivers improved latency and bandwidth at both operator and user-device levelMSR base stations are the norm in the industry, not a rarity.
If you're building new towers, things change, obviously. That said, a lot of industrial/IoT hardware still requires 4G so it's not entirely unreasonable to deploy 4G in new coverage areas.
5G RedCap is the solution, but that will need new infrastructure and chipset. LTE will stay at least for another ten years.