From a sales and statistical point of view the 30/06 has taken more big game worldwide than anyother cartridge in history, and yes the "tutty tutty" is given credit for putting the most venison on the table. As many 270s as there are around, the number of 06s is several times greater.
I have been in and around the hunting/fishing retail business here in west TN for 20 years and have seen a steady decline in use and sales of 30/30s. It's not indicative of the cartridges lack of performance or anything negative like that. I just believe it's more a victim of changing tactics like longer range hunting over foodplots, crop fields etc... I also believe the many styles of rifles on the market in basically any caliber has also cut into the 30/30 sales. 20 years ago there typically were only 1-2 basic styles of any particular gun a maker offered and very few youth guns. Now there is a FLOOD of guns of just about any convievable combination or style which makes other options for new shooters coming into the market. I realize in other parts of the country, alot of hunting is still done the exact same way it was done generations previous so the 30/30 continues to do well in those regions.
I'm not saying that the 30/30 is a "youth caliber" tho, don't get me wrong. But realistically an older shooter who already has a 30/30 is less likely to buy a new one and for the above reasons I gave, the sales of new 30/30s is slowing every year. As for ammo sales, you have to consider the number of guns already out there in the venerable old cartridge. I believe Marlin passed Winchester a few years ago in numbers of guns actually produced (336 vs 94) and when you combine the twos overall production since those models inception, I believe the number of guns exceeds the 10 million mark!!!
The top deer calibers (in both annual production numbers and ammo sales) besides the 30/06, 30/30 and 270 are the 308 and of course the 243. I believe the only magnum within sight is of course the 7mm RemMag.
Personally I prefer my 35 too the 30/30, but choices and opinions are like... well you know!

RA