Well, until they do, he is not in breach and there is nothing you can do except monitor the situation.
Not likely to happen.
If he stops paying, then you must mitigate your damages unless you have complied with CA Civil Code Section 1951.4.
http://leginfo.legislature.ca.gov/fa...§ionNum=1951.4.
Read it carefully. Have you complied with it to the letter?
If not, then you must mitigate by re-renting as soon as reasonably possible at the same or similar terms as the breaching tenant had and then you are only entitled to rent for the period from the date of the breach until the date you re-rent.
If you think suing a "successful businessman" for $40,000 isn't going to result in him getting on a plane and raising lack of mitigation as a defense, you've got another think coming.
And even if you complied with the statute and don't have to mitigate you'd be a fool to let the property sit vacant for another ten months because that's what you would have to do to be able to sue him for the balance of the lease when the lease is expired.
Meantime, your vacant property will give you problems with your insurance company and be vulnerable to vandalism.
You note that you are helping to find another tenant. Well, help harder. You haven't won the landlord lottery.