I think this move needs to happen. Oakland is consistently near the bottom in average home attendance (they were dead last this year). They are in a 50 year old stadium with sewage problems and can't get a deal done with the county for a new stadium. The Raiders and the A's are the last teams to share a football/baseball stadium and both leagues want them to have a sport specific stadium.
Metro Vegas has a population of 2MM, and attracts 40MM visitors a year. A 65K seat stadium in that market would be one of the smaller stadiums, but still matches up well with the market size and is inline with other NFL markets (Indy - 1.7MM pop, 70K seat stadium; Pittsburgh - 2.3MM pop, 68K seat stadium). Also, 25% of current Raider ticket buyers come from the LA area. Those fans would simply trade the 5 hour drive north to Oakland for a 4 hour drive east to Vegas.
The public portion of the financial package will come from an increase in hotel taxes, so it's not the locals paying for it, it's the 40MM annual visitors. And if Adelson doesn't come through on his financing, Goldman Sachs has already said they will pick up the slack. Seems like a winning deal all around.