In reply to A Latin Abugida:
According to the book "Significance of the Alphabet", by Charles Kraitsir, "The Dēva nāgari is the only scheme of writing perfectly adapted to represent to the eye the Indo-European tongues."
That's kinda weird. Devanagari can't even represent Hindi without diacritics: nuqta. The Indo-European languages have such divergent phonologies that what works for Sanskrit isn't going to be good for much else. I'd love to see the Devanagari ligature for words like "sixths" Russian "взгляд". Whenever you see the words "perfectly" and "writing" in the same sentence, beware.
The idea of using Greek letters in Latin script is not without precedent. Bruyas used θ and χ to represent [th] and [kh] in Mohawk, distinguishing them from the other allophones of /t/ and /k/.
speakers of languages such as Tibetan, Burmese, Thai, Hindi, Gujarati... could all use the same alphabet
But why would they want to? And sorry, but replacing the indigenous systems with centuries of literature with essentially a Latin script smacks of...