Global methane (aka LNG) demand is over $100 billion per year...

Yes and it's still incredibly cheap. Demand relative to supply is what you need to look at to see if we need to go to the expense and effort of making more methane out of CO2.

True about methane being questionable in itself, but converting methane to gasoline would be very useful.

https://en.m.wikipedia.org/wiki/Gas_to_liquids

Gasoline in era of EVs is nuts.

Liquified natural gas might still have few decades for certain industries, but with electrification underway for pretty much everything all these processes seem pointless.

Sure you could capture CO2 from a plant, liquify, ship to where sun shines, convert to CNG, then ship back. Or you could just build power lines.

Plastics (a petroleum product) are not useless.

Ok that's fair. Can they made by oil byproducts only or can it be eventually synthesised from CO2?

You can synthesise basically anything from CO2 and hydrogen. You can get syn-crude which can the be treated the same as regular crude. If we had "unlimited" electricity we could make basically anything from air and water.

I’d just like to support this by saying that this is what plants and micro-organisms do. They make many of our chemicals from air and water.

Yes, it's just cheaper to pump it out of the ground in a nearly ready-made state.

Read the second and third paragraphs of the article.

tl;dr: Methane conversion could be a candidate for excess energy storage technology in solar/hydro/wind power genaration.