IIRC the price point where GTL is economically viable is where oil is about $70.00/barrel. Shell must see a future where the price is near or below that.
I don’t see that happening, but it would be nice for the consumer. (But bad for producers).
It is more than a straight oil price comparison.
Essentially, the question is can you spend billions of dollars on GTL plant while buying Natual Gas at X dollars and selling product for Y dollars, versus spending the same dollars on other uses of the Natural Gas.
In a place like Qatar, where the supply of Natural Gas is many, many times greater than the demand, GTL exports competes with LNG exports. In the US, it is far more complicated with less in margins.