> if not is there really a point to include everything possible in unicode ?

Needing to load three fonts to show a single document that mixes vastly different character sets is still infinitely better than not being able to have those different characters in the same .txt or .md file at all

> how many space is remaining for new alphabet and smileys ?

Unicode can encode about 1100k code points, and about 800k of those are currently unassigned and available for future scripts or characters