This is true. However, there are multiple caveats that need to be considered:
1. A valuation is not actual money in the bank. It's a figure on a piece of paper or computer screen. It can change quickly. Anyone who has a significant portion of their wealth in the markets can certainly attest to that. Their personal "valuation" has dropped 20% in the last 3 months.
2. We've just been through a 20 year boom period in professional sports. There's no guarantee that that will continue for the next 20 years, especially for a Tier 3 market in a Tier 3 league like the NHL (it's certainly not the NFL or NBA, and not even the MLB).
3. Someone still has to service operating losses with real money every single year.
Not saying they'll sell the team, or if they do, that there won't be buyers. But it's not a guaranteed good investment, for anyone. A lot of work needs to, and will need to, go into it every single year to turn it into a good investment.