Great to hear that MAS are finally upgrading their B734 cabin! In my opinion, there should be at least a couple of B734 that offer IFEs. MAS still uses the B734 to fly to cities like Xiamen, Kaoshiung, Denpasar-Bali, Surabaya and Manila where the flying tmie is over 3 hours. But at least, you are not stucked in some dirty, old B734s. If they provide some IFEs and new cabin interiors, they could well use the B734s for another couple of years before chaing teir regional fleet. Same goes for the A330s, since all of them are relatively new.
By the way, I have to agree with Mas777 that MAS' B734 aren't that bad either, especially if you compare with European carriers. Take a look around their Business Class, and you will find the exact same seats as they are in the Economy Class, same seat width and pitch, just that you get a better meal, and you get the middle seat free, if you are flying on a B737s or the A320s family.