..But unlike bridges, I'm not sure there have been a direct attack on Wrapped tokens that resulted in loss of funds since the value these wrapped tokens have are backed by the actual collateral asset held by BitGo Trust.
As long as BitGo's collateral is in place, all is well.
However, imagine a situation where serious people came to the owners of BitGo and made them an offer they couldn't refuse.
For example, "give us the private keys to your wallets and you and your families will stay alive".
They probably use multi-signature, or different wallets are managed by different employees. In any case, this is a small number of specific people, finding them all at once is not a very difficult task for the intelligence services of any country. Organized criminals can handle it too.
The $4.4 billion BitGo has on custody is a decent slice of the pie.
What will happen to the WBTC rate if there is about 0 BTC left on BitGo bitcoin accounts ?
I don't think they will be bailed out by the government like a bank that is collapsing.
They will simply cease to exist.
All those who had WBTC on their hands can only record losses.