Its a very interesting topic.
Depends what winning is?
Selling more consoles or being the bigger eco-system? My opinion, PS5 will sell more than XB2, but I see Live becoming bigger than PSN.
The difference between the companies is MS is looking at the industry in a lot bigger way, they are aiming bigger, Sony seem to follow the traditional sense where dominating the hardware side of things brings the income etc.
MS is a lot more prepared for the bigger eco-system than Sony is right now, I personally don't think PSNow is anywhere near the same level as xCloud and I can see xCloud winning the battle of the networks. XB2 wont sell compared to the PS5 due to this reason.
Many underestimate MS in this industry, many seem to forget that Xbox has just as big if not bigger franchises under there belt as well as the additions to there studio count they have the ammo to compete with output. Also with Sony's recent anti-consumer policies and Xboxs pro-consumer polices, MS definitely have the good on there side leading into next generation. Lets not forget Sony's anti-consumer policies came from dominating the market share. If MS come out the gates strong than Sony's hand will be forced to go back to being pro-consumer so it is a good thing that both do well for the benefits of the console industry.
Its definitely not impossible especially if MS bring the games. But like I tell everyone, buy the system that suits your needs, no console is superior, they all offer different experiences and benefits.