It's only a matter of time, but the main thing is instant transactions. Several companies actually made it possible on conventional POS terminals, they instantly approve transactions without waiting for confirmation from the network, but there are certain conditions for a minimum commission.
That is where the need for the use of bitcoin lightning network to process the speedy and instant transaction, but so many companies may not be cool with that which is because of the inexperience to using Bitcoin lightning networks.As for the speed matter people don't think we will experience an instant-like transaction on bitcoin network as it's not designed for that, but thanks lightning though it has maximum limit to send but that's still a huge help.
this is actually the bottleneck here. even crypto users here in the forum, i believe, are not very familiar how to use the lightning network. so don't expect that shops and outside users will be familiar how to utilise the lightning payment method. as of now, merchants are mostly sticking to the regular bitcoin network. it will take time before we see massive adoption in lightning network. if not, we will see adoption in other alts like LTC, XRP or TRX with very low transaction fees. so right now, we can't expect full integration of btc in payment system among merchants and shops but it is already growing.
