The codebug had/has a market in that it looks small enough to incorporate into some craft type applications. I think I saw an example of it being used as an electronic dice in a board game and inserted into birthday cards with a scrolling message. However if you only have one of them then that means as a child you have to destroy your most recent artistic creation in order to create the next.
The micro:bit looks like it has a nice feature in that it can grow with you a bit as there are the four options for programming straight off. A lot will still depend upon the supporting resources for it though. Back in the 80's the BBC did something similar with the BBC Micro which was hailed a success as they launched the machine alongside a number of television programmes and text services. However at the time it was very expensive, using it with a TV screen was painful (and often had to be fitted in between family TV viewing schedules), and back in those days there were no VCR's so if you missed the TV broadcast you had to write off for a transcript of the show etc. Some code was available on text services but not many TVs had text at the time, and painful to try and copy by hand if you didn't have the optional expensive teletext add-on box.
At the start, schools only had a relatively small number of BBC micros. The best use I saw of the BBC Micro in my school was when one of the Physics teachers incorporated it in the curriculum by connecting it up to experiments and used it to produce real time graphs of acceleration alongside the manual ticker tape process. The woodworking/metalworking department had one as well and the CNC software but no CNC mills and lathes to go with it. There however was virtually no associated content to use at home even if your parents did buy one. As a result, a lot turned into games machines.
The downside to the likes of the codebug and micro:bit though is that they are reliant upon host machines for programming.
