What I'm taking from this conversation is that perhaps more folks will chose to take the T to a resort casino than I was expecting. If that is the case, I really think that the Everett location would need a major investment in that direction. Is this something that we can all agree on?
No, because its basically the same flawed logic that concluded that IKEA needed to be at Assembly Square for the T access. If you thought this, you were wrong, and we need to learn from things like this.
And no, because it seems you're either proposing a tautology (That if major investments are needed, it would need a major investment) or just getting scared/excited by the though of major transportation investments. If it isn't a tautology, too much hinges on what you "was expecting" (which is un-revealed).
Cars will work. Wynn and his target market will be happy. No traffic jams will ensue, nobody will need to be paid off with transit infrastructure any much grander than a bus shelter on Rt 99.
Casinos are not like offices or apartments that fill and empty at rush hour...they don't create peak-time trips, they create slack-time trips (noonish and midnightish) as partly confirmed by Ron Newman's Columbus Bus success). Open 24 hrs and used by people who are not at work ('cept the employees, who will ride a bus), they aren't a "gotta be there when it opens" nor a "must leave when it closes" sort of venue, and no "crap, I'm going to miss the kickoff/tipoff/overture". In fact Casinos are famously "no clocks / constant lighting" to make you lose track of time. There's no 9 and no 5.
So first, Whi and Choo and I are trying to say, Casinos don't generate jammy auto traffic--they don't generate huge throngs, and they don't have a rush that overlays everyone else's rush.
So cars will "work"...in fact for gambling trips at odd times, they work great. Unlike a show with a start-time, Wynn's Casino will hum all day, and you're free to come when traffic is light.
Pop Quiz: What day of the week sees the largest number of auto trips? Saturday! but they are spread evenly, so there's no teeth-grinding. Its busy, but it all moves along.
Second, y'all don't get the profound difference between preferring the T for work trips, and depending on it for all trips. If you have a car, Wynn wants you to drive it, and parking will likely be free. Driving your car is an easy way to show you have money to lose. A special outreach to the T-dependent is only going to get Wynn a less-rich-than-average clientele than he'd get by car or cab. Why would he want that?
Third, Choo nails is when he notes that Wynn isn't building a Casino just so he can get penny-ante $1 and $2 players, who appreciate the value of squeezing an extra trip out of a monthly T pass...the Keno parlors and scratch tickets bodegas have got that market sewn up. Wynn is selling glamour (with a u ;-) and escape...a destination and a resort.
Fourth, any who complain about the drive to Foxwoods are, lets admit it, complaining about the *length* of the drive, not the mode choice. Especially given a Central Artery that *is* free flowing at non-rush times, Wynn's Casino is like the Airport...only with free parking and no plane to catch....and in this, like IKEA Stoughton, so...
Fifth, take the two-part lesson of IKEA...(1) funky apartment dwelling, T-commuting, Mini-driving urbanites will drive when they need to to get to a unique venue and (2) the opening of the CA/T decongested north-south travel enough *at shopping times* that the Stoughton store serves the North Shore (IKEA aquired Assembly Square believing that "North" people would not drive to Stoughton...but CA/T opened and, voila, they did, and sold the site)
And, really, both IKEA and Wynn ask: if you can't be bothered to take a cab or Uber or Zipcar, how good/important/fun/free-spending a customer are you? Just as 99.99% of Prom Dates aren't going to accept "lets take the Green Line", neither does Casino culture [sic]. Basically the T+Casino market is a Venn Diagram with only Mike & Kitty Dukakis and maybe a few ArchBoston readers at the intersection.
Ergo, it will be many years before the lack of rail transit and pedestrian connections to the casino will be noticed in any commercially-significant way.