And when the next step function wave of adoption occurs, BTC will once again experience an interminable backlog of tx volume, with soaring tx fees. At which point it will 'work' only in the vaguest sense, and will be all-but-unusable. At which point, the wisdom of having stayed with the original protocol design will be revealed.
Again, the basis for your rationale depends on things you believe _will_ happen, and so far have yet to happen. Despite BTC's tx fee woes that plagued it a year ago its still by far the dominant coin in terms of popularity and BCH's market share has only decreased since then. BCH has become a tiny fraction of BTC in terms of price since Dec 2017. There's no reason to believe things will change, especially since BCH supporters are now divided into two firmly entrenched camps intent on reducing the price of the other to zero. Merchants don't want to have to set up multiple wallets to accept multiple coins -- they want one coin: bitcoin. Everything else is just an altcoin.