I have so much trouble discerning whether some of the posts on these forums are being serious or just sarcastic.
Part of the problem is that you asked for purchasing advice on an item that nobody on here truly knows what it will be.
It would be like asking if you should upgrade from a current-model Prius to the next model that hasn't been revealed yet.
While we can make assumptions, nobody can tell you for sure. So many people respond to requests-that-can't-be-seriously-answered with sarcasm.
The simple answer to "should I upgrade from <x> to <y>?" is nearly always "if you will get the extra value out of it that it will cost to upgrade, sure."
The iPad 5 will almost certainly contain the new 64-bit CPU. There are a few (very few) applications for the iPhone 5S that have already been announced that take enough advantage of the 64-bit instruction set to allow for new features they can't do on the older 32-bit instruction set. If those features are something you would find useful enough to justify the upgrade cost, then it's worth it. (One example was a video DJ app that can do multiple 1080p streams at once.)
As for "keeping my losses to a premium," I still have an original iPad. It is still useful to me. I will likely keep it until it either stops working, or there are software reasons for me to upgrade. But let's say I pick this year to upgrade to the iPad 5. I paid $500 for mine in late 2010. I got three good years' use out of it. That is approximately $170/year to use. If I had upgraded to the $500 model each year, and sold the prior one for $400 (extremely unlikely,) then I would have spent a total of $700 over three years (before buying this year's - the original $500, plus a net $100 to upgrade to an iPad 2, plus a net $100 to upgrade to an iPad 4 - skipping the 3 based on my purchase cycle.) That is about $230 per year to use. So from a "keeping my losses to a minimum," perspective, if I had no compelling software reasons to upgrade, it made more financial sense to stick with the old one.
So, when the new one comes out - look at the software. If software you need/desire comes out that requires the new iPad, then by all means, upgrade. But upgrading "to get the most out of selling my old one" will always be a money loser, since you are not going to get your original purchase price out of the old one.