yes, anyone who has access to your encrypted wallet.dat can try brute force the pass. But if your pass is original, and strong (various combination of numbers, special signs, min. 8 char. long) there is nothing to worry about.
also do not say to anybody how much btc this wallet control. no loot = nobody will try to break pass.
If you have access to the wallet.dat file, it won't be diffcult to dump out the encrypted information for you to see (even though your wallet is encrypted with a strong password). Then we can see which address that holds the money. Once it is found, use blockchain to know how much money in there.
I would say difficulty depends on password length and complexity. I personally would make new wallet send BTC to it and encrypt it, and turn on two factor authentication.