Locals me how big The Knights are in Vegas? How has the youth hockey grow in Vegas and What kind if potential are Vegas in general to come a hockey town?
Are people interested hockey when the team is poor and wont succeeded anymore?
We won't find this out until the team does end up turning into complete shit. Hopefully it doesn't, but the majority of teams usually do end up going through periods of shit play (aka rebuilds).
The true test of a fanbase is how they react to their team being complete garbage.
For a team to be successful in an area (through good times and bad), there has to be both an organic (natural) fan interest in the sport, as well as a willingness for a team to embrace the community.
In may surprise many people, but Las Vegas had an ECHL team from 2003-2014. (The ECHL is a tier below the AHL. The AHL is the primary professional developmental league for the NHL.) So, Las Vegas had a fan base that was primed to accept an NHL team. Others can write about the youth league teams in the city.
The Knights have certainly made an effort to make itself popular in the community and to be involved in community activities.
Let's contrast the Vegas Knights with the the NFL American football team, the Los Angeles Chargers. The Chargers recently moved from San Diego and their move will probably be a fiasco. The Chargers are competing against another new NFL team in Los Angeles, the Los Angeles Rams. The Rams had a history in the city (1946-1994) before leaving, so they have a previous fan base. There is no connection between the Chargers and the city of Los Angeles. Furthermore, the demographics of the city have changed, so I doubt there is a sufficiently large enough fan base to support two NFL teams. The Chargers will be the losers. Visiting fan bases have heavily populated both teams' stadiums. (The Chargers are far more impacted by poor attendance than the Rams, however.)
I don't think I've ever seen anyone outside the stadium wearing Los Angeles Chargers clothing. Rams team clothing is not too unusual.
If the Vegas Knights have a run of losing seasons, they will also be competing for fan interest from the newly-arrived NFL Las Vegas Raiders. Also, the planned AHL team will possibly divert some interest. That said, the games would continue to be popular because the fan base of opposing teams will replace the locals at games.