robbed,
I don't get real excited about the rumor OTHER than the potential additional short term capacity might provide for accelerated int'l growth because there are 346s readily available.
If the 744s are due for overhauls within the next five years, it is very likely they will get parked at that point.
most other carriers have or will remove their 744s from their fleets; if Japan was booming, it might make sense to keep them going but DL is going to reduce connecting capacity thru NRT and downsize aircraft to retain only as much of the local market as it needs to serve in order to be profitable and still the dominant airline between the US and Japan (and DL's fare advantage comes from its dominant service position which is why those who think DL will cancel routes instead of downgrade to lower cost equipment don't understand the situation).
I'm not even sure an aircraft the size of the 346 makes sense; but I am sure there are routes which are ready for upgrades but for which the 744 is too big and too costly of an aircraft.
remember that if fuel prices go up, a lot of routes won't work, regardless of the aircraft that operate them.
the whole reason for having some cheap int'l capacity is that those planes can be easily parked with little risk. If you are paying $750,000/month or more for a 777, 787, or 350, it costs you a lot of money to not fly aircraft.
The M80s are now the "flex" capacity in DL's domestic fleet since the DC9s are gone. If the economy goes south, the M80s can be parked because they are largely no-cost aircraft.
If the 346s come, it will be because DL has a maintenance holiday on them and they are cheap enough that DL can grow now and get rid of them at little cost, ordering newer aircraft when the industry is more stable.
With UA struggling, it is far from certain how the int'l market esp. will look in a few years.