If it does come to that point Blizzard will likely nerf it or remove it entirely. Just look at what they did to Corpse Explosion and Outbreak - they didnt think Explosion was versatile enough so they chucked it to possibly be reborn as a glyph and Outbreak was too versatile to leave the class without it so they made it baseline again.

Keep in mind they are also discussing ways to change talents more readily, something along the lines of the current glyph system. So it may come to pass that we are able to change our talents as easily as we change glyphs. I cant imagine that on every fight would Shuriken Toss necessarily be the most useful. Maybe the boss is in range for the vast majority of the fight or maybe theres a deadly add phase where interrupting may considerably reduce the need for healing on the tanks, no one knows.

Alas, Blizzard may end up moving the spell to another tier in the tree, or change one of the competing talents to make it more attractive. Im certain they will listen to the rogue communities concerns and address them accordingly. Of course, as a Death Knight mainly, I still dont have any hope for our tier 5 choices. Not very interesting choices at all.

On a seperate note: When I was playing my twink rogue and warrior and again when I leveled them I used to have the greatest fun when someone was almost dead (namely the squishy mage XD ) and they would root me thinking they had escaped, only for me to whip out my bow or shuriken and finish them off! lol I could only sit there and imagine what must have went through their minds when they realized they were dead