Talk in the AC forum of new AC baggage limits coming into effect in October, so as I have a RTW in November coming up, I've checked up with the local AC call centre to see if this affects RTW trips.
According to the information the local call centre has received, it appears to be a network wide adjustment and the new 23kg/50lb max weight per bag (still 2 pieces per person) applies to all AC flights, including those as part of a RTW.
Bags weighing between 23kg-32kg will be charged a new flat rate of CAD60.00/USD50.00 worldwide for International flights and CAD35.00/USD30.00 for Canada domestic & flights between Canada -
U.S./Mexico/Alaska/Hawaii.
Bags over 32kg will *not* be carried at all & must be booked as cargo.
Linear measurements remain at 62"/158cm (LxWxD).

One bright spot - according to their info, the *G allowance remains at 3 pieces, albeit at the new weight limits.

From memory CO and NW also recently reduced their bag limits to the same levels, so looks like the start of a new trend, although the Nth Am carriers have always done things a little differently than carriers in other parts of the world. Wonder if this new Nth Am baggage initiative will spread or not?

That's a bummer....I can't remember the last time any of my suitcase's weights started with a 2......

does this include codeshare flights?

Yes this would apply to all flights where AC is the operating carrier.

I just don't understand what the airlines hope to achieve from these changes to baggage weight limits: do they expect to generate extra revenue or dissuade people from over-packing and thus reduce weight and save fuel?

All I see happening is that people that normally use one suitcase will now probably need to use two to stay within the limits. This will increase the volume of baggage and increase the weight (extra case) thereby reducing space in the cargo hold.

Pity the poor leisure traveller or anyone travelling with kids - now there are more bags to contend with.

Yes, on both counts.

I saw it coming a few months ago when I heard reports of stricter enforcement of current limits... Can't say that I'm surprised.