The main Madagascan language (Malagasy) falls under the Austronesian language tree. So with a POD of before 1900, bring Madagascar more into the Austronesian sphere (whether this is in terms of trade, travel etc).
What do you mean by "Austronesian Sphere"? There was historically no contact between say, New Zealand and the Philippines. Do you mean something like "Malay Sphere" or "Southeast Asia Sphere"?
Could be, but a more developed Austronesian sphere would be neat. Certainly would help the dreadful language situation (1256 languages!!! with a massive majority not even being spoken by more than 500k ppl)
What do you mean by "Austronesian Sphere"? There was historically no contact between say, New Zealand and the Philippines. Do you mean something like "Malay Sphere" or "Southeast Asia Sphere"?
Well kind of the south-east asian sphere and/or the pacific sphere (if that still exists, with Aus, NZ and the pacific islands) pretty much i.e. Austronesia as a whole.