It will launch head to head. Those of you who think that Sony will destroy them again need to look at your history. Look at the generation's starting from NES until now. How many times has the same company dominated twice? Just once. That's it. In all of gaming history, only one time has the same company dominated two times in a row in home consoles.
Even at best MS (360) had a hard time beating playstation (PS3) in its worst gen. Ps3 arguably sold more with one year less on the market.. so when did sony fail?? and when did MS won?? IMO Playstation has been a force to reckon with, since past 4 gen.. its just that blunder of PS3 launch and a year early launch made Xbox competitive against PS3. Playstation is such a strong brand that it survived those initial mess up, but in the similar scenario xbox one struggled to even match PS4.
Not to mention all the digital games and back ward compatibility will give enough incentive for 80m consumer to go with PS5 next gen, Xbox currently doesnt provide any incentive as to why I as a consumer should jump ship, I am just not going to rebuy all the games that i have accumulated on PS4..
the only way sony can mess up PS5 is if they restrict backward compatibility in any form. like if its only digital and no disc based, something like on PS4, no Support for PS2 and PS1 discs! The biggest trump card MS is going to have will be their BC.