The fact remains that this does not mean a refresh in April unless Apple can offer a processor with better GPU performance than the standard A5 & A6 that is not as power hungry as the A5X and A6X.
1 component in development (NOTE! DEVELOPMENT not production) does not constitute a sure fire refresh with retina.
The A5X & A6X are criminally power hungry hence the increased battery capacity of the iPad 3 & 4 over the iPad 2 which still resulted in less battery life and extra weight to the device.
The Mini in it's current form needs the power of those chipsets, but one that isn't compromised in both battery and thickness, and currently that doesn't exist.
The iPhone 5's A6 on it's own isn't powerful enough to drive the 2048 x 1536 screen resolution (hence the A6X). In fact the iPhone 5's 1136 x 640 resolution is actually 50,000 pixels smaller than the iPad mini's 1024 x 768 currently.
So assume Apple manage to make a revision to the A6 that does add more power to it's gpu without needing a 45W battery (3x the capacity of the iPad mini which gets 2 hours more battery life in real world tests).
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That may all come together next year, it may not.
Remeber also in their cheaper hardware Apple like to use 'previous gen' CPU's so iPad Mini 2 (or new iPad mini) may just get a bump to a standard A6 as found in the iPhone, but that on it's own may again not be enough to drive that display.
The chances of them refreshing the iPad, iPhone 5s/6 & iPad mini with a newer A7 chip is slim.
Good Points...
BOTOH, Apple now has no barrier to do this, other than the hard work. I wouldn't be surprised if their chip roadmap starts optimizing to the 3 form factors, thus having an A6, A6X, and and A6Y (a Y maybe with only 3GPUs instead of 4, and other power saving modes.
this isn't like waiting for Intel to push a chipset.
The battery tech is also a key item, as well as the performance (draw) of the screen). The nice thing about Apple is that they can build to spec, with cash, and get a custom glass, custom battery, and custom SoC. this is how they built the original iPad, and set the industry on their ear. At this point, only Samsung is cash capable of building to spec.
That is why I think there may even be MiniRD price bump to $350, (and no possible way they move it to $299 for the 'top of line' Mini), to pay for some of that technology, and the current Mini then drops to $249, still allowing for a 30% Margin. at $249, 349, 429, 499, that's a pretty tight pricing curve allows no one (Microsoft) to find a niche.
If Google can make a iPad Mini competitor and sell it for $199 and make money doing it... more power to them.