BenQ, as is often the case, doesn't publish much information on upcoming models. This is typical for many manufacturers until a product has a set release date. I would expect that BenQ will have a production 4K model at some point, but how soon that would be is an unknown.
There are a lot of manufacturers who are making bright DLP models which are alternatives to the BenQ models.
https://www.projectorcentral.com/projectors.cfm?g=2&r=1017&br=6000&br=10000<g=101&dt=3.0.0&exp2=1&vls=1&oop=3#list
Digital Projection, Barco, and Panasonic are going to hit more towards the high end, while LG and Optoma also have options which slot into the same space as those BenQ models. This model, specifically, is one that I would very seriously consider as a drop in replacement option:
Panasonic PT-FRQ60WU7 projector specs, projector reviews and current street prices.
www.projectorcentral.com