It certainly won't be like gold

Simply because gold has unique properties that no other metal or substance can reproduce. By and large, Bitcoin is essentially just one cryptocurrency among many others out there. It enjoys the first-mover advantage, of course, but this is obviously not enough to always stay at the top. In fact, I can tell what will happen if Bitcoin fails to scale. It will first stagnate with it price lacking enough growth, then its profitability will start to suck, and after that people will massively dump their Bitcoin stashes in favor of more profitable coins which don't fail to keep up with the progress (evidently, not limited to solving just scalability issues)