I hope someone is doing a carefully controlled sonar survey of the area where contact was originally lost.
The problem is the sea between Thailand, Vietnam and Malaysia is like a puddle. It's extremely shallow, about 200 feet deep, and likely full of junk already. You can't easily use sonar. If no-one finds any debris soon, then the wreckage is probably going to be found accidentally in the end by being snagged by a fishing net.
It might also still have been moving fast enough on impact in shallow water that it embedded itself in the mud on the sea bed, muffling any pingers.
Without better inferred positions from radar and radio transmission records, the search for the wreckage may be a long one.