We got that already, in principle. We have several APP control positions that cover a range of airports top-down. And as David has written in VATGER finally a speedier progression from zero to S1 (restricted to small airfields) through online-courses only has led to good local coverage up to TWR level. With such coverage an APP controller can easily manage 5 or more airfields.
in buisey airspaces with minimal control i will text to anounce myself and basic intentions and adhere to f/plan eventualy they will get to me via text or radio…having several pilots talking same time to atc is a problem but it works itself out in the end… 
I can understand why you think sending a text message to notify a busy controller is a good idea as a pilot, but as a controller, I’ll say that text chat is generally the first thing to be ignored completely once it gets busy.
If and when we do see text, it will usually take us more time to read and deal with it than a voice message will, especially as we have to double-check if the information in it may or may not be outdated already, and all that time with our eyes away from the area of responsibility is time that we can’t use to scan our sector, work the traffic and safely get everyone where they need or want to be, so you’re really just adding onto the already high workload of a controller. 
The exception, however, can be PDC and CPDLC. We’ll still need a verbal check-in before using CPDLC, but after that, due to direct integration into the tag (at least in the setup I’m familiar with) it’s very easy to send non-time critical instructions via datalink, and it helps tremendously to shed workload off the frequency.
Wasn’t he talking about text on UNICOM?