I strongly believe that if some well known investors come in and buy billion dollars worth of bitcoin it could be world breaking news and the price of bitcoin would soar high to $10000, just my opinion.
Definitely it would make bitcoin price to increase since more investors would invest in bitcoin.But it would last for only small time and as soon as a rumour hits the bitcoin environment,all of them would start selling their bitcoins which would make bitcoin price to fall down.It would be better if they stay away from bitcoin.