Localbitcoins lost their trading volume because they used to be a p2p BTC exchange that later began to ask for KYC from their customers, their users were people who wanted to trade only p2p, so obviously trading volume was going to drop, as their customers moved to other BTC p2p exchanges.
When a service was created to give privacy and ends up having to remove it, this was the biggest mistake of localbitcoin. In the wake of this closure, others will benefit such as Bisq, Robosats and even Peach.
It was also quite the monopoly of the P2P Bitcoin market which I never liked, so better that it shut down and paved the way for better alternatives. Similar to when there was a monopoly over a centralised exchange like MtGox, a darkweb market like Silk Road, a Bitcoin mixer like ChipMixer, or any other Bitcoin-based service. The ecosystem only gets stronger once the leading horse is taken down and the monopoly ends.