Except every item that has gameplay stats are gonna be available through ingame means.
But to get them all will take a long time going by in-game means alone, whether you're waiting for them to drop, gathering materials to craft the ones with recipes (which you may already have enough of if you've been stocking up; still a fuckton of materials considering most of the new recipes involve
two Reclaimed Metals), or trading for them (which requires something that the trader views as equally valuable).
I am hoping they (temporarily?) increase drop rates (which they very well may do for Christmas Day or something as a "gift").
Fun fact: The Loch-n-Load currently has 2 recipes that yield the same result with no other possibilities, but one requires several less weapons. This is because it has its own personal recipe as well as the "Fabricate Class Weapon" recipe. The personal recipe (Scottish Resistance + 2 Reclaimed Metals) requires a total of 13 weapons (1 SR + 2 (3(2)), while the generic Fabricate Class Weapon recipe (Class Token + Slot Token + Scrap Metal) requires a total of 8 weapons ((3(Demoman weapons)) + (3(Secondary Weapons) + 2).
I say they should cut the hat out of the already existing item set bonuses. Everybody who's purchased one already can get some free keys or something as a pseudo-refund.
Yeah, I think the only reason they haven't done away with the hats from the original Polycount update sets is because they've gone on for months accepting money and having people crafting those hats just for the bonuses. The people who bought a Polycount hat and the people who spent a long while getting the weapons for hats they didn't necessarily like aesthetically would be in an uproar if they did away with the hats being required for the original bonuses. And if I had bought the hats just for the bonuses, I'd be kind of pissed if I got a few measly keys as compensation for Valve removing the hat requirement.
My solution (which I highly doubt has not been proposed before) is to have a slightly weaker form of the bonus for the original sets if the hats are not there, to resemble the more mundane bonuses of the Australian Christmas packs. For example, the Tank Buster set for the Soldier. Currently, with the hat, the bonus is +20% Sentry damage resistance. Without the hat, the bonus could be something like +10% Sentry damage resistance, which closely resembles the +10% fire damage resistance of the Demo's hatless set. For the Scout's set, +12/13 Health instead of +25. For the Pyro, +5% move speed and bullet vulnerability instead of +10%.
The Australian Christmas sets could also be boosted with the hat, encouraging sales of those hats. +2 heath regeneration per second for the Medic instead of +1, +10% critical hit damage resistance for the Heavy instead of +5%, and make the Demo the ultimate in resisting the Pyro by making it +20% fire damage resistance instead of +10% (it's cumulative with the Targe's +50%). And of course these are all just numbers for the ideas.
The 2 sets that would present a problem with this idea are the Spy's set and the Sniper's set. For the Sniper, it's hard to reduce a "wearer cannot be killed by headshots" effect without boosting the original, or going in a completely different direction. One thing about the Sniper set is that the bonus compensates for the effect of the required weapon Sydney Sleeper, which itself cannot headshot. The Bushwacka in the same set has a +20% fire damage
vulnerability attached to it. Perhaps the hatless effect could be +10% fire damage
resistance or somesuch, for a cumulative effect of +10% fire damage vulnerability? It's not immunity from enemy Sniper's headshots, but it does compensate for one of the required weapons. Though this is arguably the better bonus, as enemy Snipers typically just bodyshot Snipers wearing the Ol' Snaggletooth hat anyway.
For the Spy, the "Reduced decloak sound volume and 0.5 second longer Cloak blink time" effect doesn't translate very well to having the effect lowered or changed in a similar theme. I've got no ideas for an effect for this set. It would probably need to be something dealing with cloak, but the current effect kind of has that covered.