[quote=“harding, post:10, topic:1470”] That is, they need to be direct users of Bitcoin Core and have their wallet connected to their node. [/quote]
A pedantic point, there is no necessity to have the wallet directly connected to the node (e.g through SSH or Wireguard), as long as you can feed it with the block updates with whatever communication channel, including one-shot USB sticks. That was the idea with multiprocess to not have the node and the wallet running in the same memory space, generally more wallet and node hosts are dissociated better you’re are.
Otherwise, I agree a lot with what Dave says and that a greater percentage of Bitcoin users validating their transactions with their own full node is the key metric that matters.
No hard fork or soft fork required at all to have inter-compatible clients with Core, if this the question. And the bar has been reduced by many order of magnitude with the [libbitcoinkernel](https://github.com/bitcoin/bitcoin/issues/24303) becoming mature. It’s supposed to be a standalone library encompassing all bitcoin consensus rules, and you’re free to re-write all the others components as you wish. If you find consensus bugs or DDoS issues while hacking on libbitcoinkernel be at minima responsible and report them.