Not in my opinion. Relatively speaking, I though the iPad 4 was one of the BEST. Insane battery life (13-14+ hours) and performance.
Others don't agree with me, but I look primarily at RAM as an indicator as to when to buy. I buy at the BEGINNING of an upgraded RAM phase. That allowed me to skip on the iPad 3, iPad Air 1, and iPad Pro 9.7. I own every generation iPad except those and they are still in daily use.
That is what I use to help me to determine WHAT to buy.
As for WHEN...
After the first gen iPad (which I had on preorder on day of announcement), I have a rule to wait 3-5 months after the availability of a new generation iPad. This allows those units manufactured during the run-up to release to be sold and cleared out of the retail channels. That first batch has a higher than average probability of manufacturing issues. During that first batch, issues are identified (most common are recalibrating of equipment) and resolved. Units from later batches, generally speaking have higher build quality.
This is why it is important, IMO, to determine how much RAM is in the 10.5 iPP. If it is 2GB, then according to my guidelines, it is a no-go. I would wait until the 10.5 iPP shipped with 4GB. If it is 3GB, then considering screen resolution in comparison to the 12.9 Pro, that would be a "solid buy". Relatively speaking, it'll have the same RAM "headroom" as the 12.9 Pro and the same longevity. If the 10.5 has 4GB, then it would be a "must buy" as it would have a GREATER headroom than the 12.9 Pro.
Others are free to use them or disagree.... but it has worked personally for me and I'm stickin' with "what works".
Oh, to answer the question: No there will be no new iPads in October. There is a longshot possibility of an update Mini (with the Mini 4 dropping in price in time for the holiday season)