If possible I would like to get an educated answer to this.
LAS is a great route for VS. Daily flight is always busy. BA are now flying to LAS from LGW and LHR. So there must be some form of demand there.
If not an american carrier but why has EI not jumped on this route yet, even 3 a week.
Heavily leisure traffic and price sensitive, EI would find it difficult to make to work however now with feed it would be more viable. US carriers and BA/VS have good deals with agents to route traffic via a certain point and it could be difficult for EI to undercut those and remain viable with a direct service.
It's similar to Florida, thousands fly via MAN/LGW and the US yet EI have a low frequency direct service. If it was worth their while to claw back those passengers they would but guess more money to be make elsewhere.