No, it wouldn't, due to Fractal. Fractalling Scarabs is better in all cases, and would probably still be after the cost of Pharaoh had been lowered by 2. FFQ would still be used in rainbows due to quanta distribution and higher attack of Elite Fireflies.
Giving Pharaoh more HP won't help one bit. Very seldom is it killed, but rather frozen, delayed, lobotomised, etc. Since it produces decent attackers, it wouldn't make sense to buff its attack, and Elite Mummy is an excellent rush card.
Fractaling Scarabs is better than spawning them with Pharaoh if you want to have a board full of Scarabs. Fractaling Fireflies is better than spawning them with FFQ if you want to have a board full of Fireflies.
Because you think that fractaling Scarabs is better strategy in all cases than spawning them from Pharaoh, doesnt mean practically anything in an argument that Pharaoh at 7 cost is simply a better creature than FFQ.
What I am saying that
Pharaohs generate much stronger threat than FFQ, and they do it using their own element. It is a pretty simple sentence.
As for what CC is used on Pharaoh, that depends on the deck you're up against. You wont freeze, delay or lobo my Pharaoh if you dont have it in your deck. If you do, you'll do the same to practically any creature I field. 8 HP is right there on the border of "should I bother to waste my CC on this dude", but when that dude is spawning devouring army, I'll sure make sure to take him out in any way possible. Especially if something like SoR is played on him. I'll definitely be more inclined to pack SoRs in Pharaoh deck if he had say 15 HP.
Elite Mummy competes with Flesh Recluse for a place in a deck. Its identical in every way except it has weaker attack, so its selling point should obviously be that it turns to Pharaoh when rewound. However, that Pharaoh has even lower attack than Mummy, and his ability will be useless to you.