You're absolutely spot on, what we need to understand is that the cryptocurrency and Blockchain Technology is relatively a very new tech and still have room for future advancement and development. While it's true that there's has been yet no proof or official publications of alternative methods and ways to send and receive crypto without the internet, I strongly believe that the Devs are working seriously on this and I'm the nearest future, with how technology is fast developing, they'll be able to give us a positive result on this.
It's indeed gonna be a milestone if they're able to achieve this because it's gonna be solving a lot of problems and difficulties people encounter, like being somewhere having or experiencing internet outage and other scenarios.
I don't think going offline or making offline crypto transactions would be a good option or possible, though we can't underrate the future and its potentials but, if that is possible then the new development would have to work separately from the Blockchain, which might not be safe or difficult to for hackers to get in. Working without the internet and similar to going blind, I hope we never have such experience were the internet would go blackout, because majority of our day to day activities are being carried out with internet connection. The internet is the future, even fiat banking system are being operated online so cryptocurrency wouldn't be the only currency to be affected because it is fully digitalized.
Yes it's true that the internet has already become a very essential part of our lives, but that doesn't mean that we have to overlook the vulnerabilities as well as the flaws that's associated with the internet. Let's take for instance, if a global internet outage is to occur ( although very unlikely to) just imagine the fate of the world at that point.
Making offline transactions could just be what the world needs, especially with the development of other technologies like the mesh network, offline wallets that are Blockchain based and also other decentralized alternative solutions.
This could turn out to be the best innovation the whole needs and can ever see in the crypto space, because being offline could be a very incredible way to keep your funds safe and free from online Hackers, as well as to provide a more resilient mode of transacting.