the alg changed but the price did not change anything! why?
Algo change has no relationship to the price i would say. Mining is efficient, so people rather mine than buy at the moment. Maybe when diff is higher the price will also rise.
Will we see 1 Dollar again?
In my opinion, mining just switched from asic owners to gpu owners. Buyers did not change. There's no reason the price would change unless gpu miners dumping mentality differs from asic miners. Regardless, we are mining now so price increase would be nice!