The master chief collection is a part of Microsoft plan to bring 360 players to xbone. There no need to counter that. COD is also on PS4, but I would advise Sony to release the MMOFPS PlanetSide 2 on PS4 before Christmas.

lol come on how about get real bud, Halo is a bit bigger but the way you are talking is as if you are comapring Uncharted to freaking GTA.

Halo mcc is barely a glacing jab much to do with PS4 just being a beast and not halo not being big.    

Sony shouldn't chase MS modifying its release schedule, as it would be perceived as a sign of weakness and insecurity, not to mention that Sony's goals are profit, revenue and leadership, to be obtained selling more HW and SW than MS, not damaging it and making it sell less, except when really competing to get the same users, so a frontal attack should be avoided if not absolutely necessary. In Halo case, it's MS exclusive, so Sony really can't get its fans in any way until the series naturally fades away. But in all these cases Sony can do a thing, boosting marketing if and when necessary, and in this particular case, as Halo fans are generally quite far from perfectly overlapping with GTA ones, let alone LBP ones, advertising more LBP and some deals with Rockstar, for a PS4 GTA V bundle or for some exclusive advertising could be a good idea.
Another good idea, considering that PS4 could already be supply-constrained for Xmas, could be some( obviously cheaper, both from being in a slow period and less intensive) advertising after the holidays, to help PS4 suffering from a smaller drop than competitors during the slow season.
Sony could also select some skilled indies and give them dev kits and maybe some small funds too to develop PS4-PSV cross-platform titles. With $2M it could support 50 devs with $40k each and it could make the deal even more appealing giving their existing titles (the ones their selection should be based on) more visibility on PSN, so helping supporting them during the development of the new titles without having to actually allocate bigger funds from its cash ($2M, 50 devs and $40k each are examples, Sony could devise the appropriate numbers). This particular plan would help PS4 and even more PSV, allowing Sony to allocate funds for its support that PSV by itself couldn't justify or at best could recoup quite slowly unless sales really take off in an impressive way, and it could also help selecting a few ones to make a longer leap to become bigger dev studios in Sony's sphere of influence.

Halo 4 sold very well, yes, but look at how fast it's community evaporated. Halo no longer holds the same MP pull it once did, and I think we will see that effect continue into Halo 5 which will still be a system seller, just no Halo 3 unless it's somehow a masterpiece

So if one game loses some of the community it will never get it back? This surprises me, somehow.

But let's not talk ifs and whens, let the game release with some decent marketing and let's see what happens.

You're wrong. Uncharted is huge as well, while not as big as Halo it still huge, and can match upto Halo in sales this gen.

Besides, its not even Sony's biggest IP

Unless MCC collections can push out like 5 million consoles before the end of the year, I doubt sony is too worried. They got DriveClub and LBP. They aren't huge system seller, if at all, but they are coming in with mild hype.

Driveclub CAN be a huge system seller as it can draw many racing game fans to the console. It can also give a massive boost to PS Plus subscriptions on PS4.  That really depends on its critical reception though.

ok, its still on decline. didnt make my statement wrong at all. And that was on a install base of about 80mil. I wonder how well Halo will do now on a smaller install base, still good but I dont think it will put up the numbers it did at its peak.

Collection is still missing games, Reach to me in particular since IMHO that was the best one made since 3. So for me even if i was insterested i would skip the collection since they are missing the best one. again just my opinion

once a series starts a steady decline its hard for it to go back up to its peak numbers or above. The only series i know in recent years that have done this is Assassin's Creed with 3 but even then the numbers went back down. Not saying Halo cant do the same but its going to be harder for one i imagine 5 will be seling to at smaller less popular system than 360 was.