We have two scenarios for it. A ps1 and ps2 scenario where Sony reposition ps4 as an entry level Playstation experience with aggressive price cuts both on hardware and software mainly to appeal to emergent markets where most people don't have income to afford a new Gen console and games.

Or the ps3 scenario, where Sony pretty much abandoned it once they saw ps4 juggernaut success.

For the way things are going for ps4, I believe it will be the first case. We are getting very big releases this year just months away from ps5 release. And I think ps4 has room to agressive price cut, it can go as low as 149 usd for base model considering it uses low end hardware by today standards. 

The same way they handled the Ps2 and Ps3 - They'll lower the price and just keep selling them. Ps3 sold well after the Ps4 Launch.

Hard to say. PS4 has not followed the same path as PS1 - PS3, so it is difficult to predict what they will do going forward.

If they went the same path as previous PlayStations, then I would expect a Super Slim model at some point, that could start at $199.99 and eventually drop to $149.99. I would like to see them do the same with PS4, and keep it on the market another 3 - 5 years.

Sony will likely maintain their min. 10yr support on the system so we'll still see the PS4 in stores but at a lower cost and will still get some new games here and there until 2023.

They ll drop prices and keep selling them.
3rd party will do most of the work supporting it, post PS5 release.

I would like to see them do a perm drop to 199$, and have holidays at 149$ for a PS4.

Ps4? Never heard of it

It will be just like ps3, ps4 will have a quick death, perhaps even faster death than ps3.

I think they will drop the PS4 support. Ghost Of Tsushima will be their last big game for the system, Third parties will still keep it going for a few years though.

Times have changed, it will be quickly dropped.

I think it'll live on for much longer than the PS3 did.
Sony arnt makeing huge losses on sales with it.
Even at 199$ there is profits to be made.... at 149$ it might be barely break even or perphaps have a slight loss.

Ontop of that, its library is better than the PS3's was, and if it goes that cheap, theres bound to still be some late adapters to it (much like the PS2).
plus alot of the GPU grunt, of the next gen will go towards running 4k resolutions and perphaps 60fps + raytraceing.
Allowing for older gen consoles to run some of the games at say 900-1080p, and 30fps (and without raytraceing).
3rd party support will keep it going for awhile.

Also with the economy the way it is, I think theres a market for a super cheap console, with a huge library of then (cheap games).