BBC News 24 need to bring in the presentation dudes at World!
The presentation dudes as you call them are the same! The same head of presentation is in charge of all the graphics/look of all of BBC News output on World, News 24 and Nationals!!!
Also adding to what I said earlier you are not going to get a joint News 24/World because it would go against the nature of the two channels ... take for example The Budget - a huge domestic story, of no interest really to the rest of the world, the same applies to most political stories. The BBC remit for News 24 would not stand up.
Expect more World programmes on BBC 4 - which will save some money.
Also merging pres styles (eg generic BBC News titles all the time) would save peanuts ... that's not what costs the money - it's people that cost money and newsgathering.