As for the displays, there won’t be changes (technologically speaking) because, according to some reports, the new displays will be similar to the 24-inch ones that currently exist in the market, which were introduced in October 2008.
With this, the company would pretend to introduce another additional screen with similar size to the 27-inch iMacs that have had a successful reception. This thinking is really logic, so the introduction of a device with these characteristics to generate some additional money for Jobs and his company is not an unrealistic plan, but rather a reasonable move.
But why now and not before? Well, a possible reason is that Apple would have been waiting for a fall in the high price of LCD panels that support a resolution of 2560 x 1440 pixels, but apparently, the new products are being developed since a long time ago.
On the other hand, regarding the Mac Pro computers, the updates are related to the use of Intel Xeon Processors: The Xeon 5600 Series (12 cores) will be used in new Mac Pro models, while another version will be using a single processor model, with only six cores and a lower price.