No one knows when (or even if) the old APs will be reprinted to meet the new distribution model. When I messaged FFG about it, they replied saying it was "undecided," though they'd announce it immediately if ever they committed to changing the way the old packs are printed.
I'm just getting into CoC myself, so I too was hoping the reprints of the early Asylum Packs would be rejiggered to include the 60-card format. Even so, I've made a few purchases to expand my collection as I don't have the patience to sit around waiting for an announcement that might never come. Personally, I think it WILL come. Some day. But when ...? There's no way of knowing.
I currently have:
Core set (of course). I will be picking up a second very soon, and likely a third down the road.
I intend to pick up a copy of Arkham Secrets as soon as it releases. That's a safe bet. I'll be splitting a second box with a friend who also plays, to max out my multiples.
Also, I recently ordered:
Spawn of the Sleeper
Path to Y'ha-Nthlei
Journey to Unknown Kadath
The first and last APs in each series seem in include a number of key cards. I wasn't sure about purchasing Spawn of the Sleeper as it's currently slated for reprint; as are many of the early packs, from At the Mountain of Madness through to Antediluvian Dreams. Who knows? Maybe they'll hit the shelves in new format and I'll feel ripped off. I'm convinced it will happen eventually, but there's no guarantee it'll be soon. Beyond that, the only packs 100% confirmed to be 60-card are those in the the new Yuggoth Contract series (not yet released).
As I continue to collect, I'll likely stick with no more than one of each 40-card AP until FFG starts cranking them out in full triplicate. If you prefer to err on the side of caution, buy multiple Core Sets, grab Arkham Secrets when it releases and start snapping up the Yuggoth Contract in the very near future. Maybe you can avoid the old APs until FFG is able to draw up new contracts for new cycles.