I dunno, which is the hard thing. We need (a) decentralized coinjoin in many wallets, but the protocol for that has to exist, (b) PayJoin/silent addresses/etc in many wallets, (c) LSPs for mobile lightning nodes (or many a compelling path to pleb LSPs?), (d) Sv2 adoption from miners and pools, (e) probably more? All those things feel like uphill battles.