Bitcoin will continue increasing. This increase in price will lead to a price of $500 to $600 after halving. If a stable growth is experienced after halving $800 will be reached in a year's time.
I know the price of bitcoin will go up. And yes a figure around the 600 mark is very realistic if you aim for the end of this year.
But 800 is just too much. It would have mean that the price will double in 9 months. And no i don't see this happening.
In a way it isn't totally unrealistic to see a double of the price after a halving event, but I would say that it is very unlikely for such a thing to occur.
There hasn't been a halving on this scale before, however, with such a massive market cap. For all we know anything can happen.