The nRF24 is simple to work with and very versatile.
However Nordic recommends that the nRF24L01+ should not be used in new designs so, presumably, they have plans to discontinue production at some time in the future. However the nRF52xx devices that they recommend for new designs are conceptually completely different as they include micro-processors. The few breakout boards that are available for the nRF52xx devices are physically a great deal bigger than the common nRF24 modules which makes them unsuitable for small projects. As well as which they are a lot more expensive.
It is possible to make a very small wireless package with an ESP8266-07 using ESP-NOW but it uses a great deal more energy than the combination of an nRF24 and an Attiny - presumably because its clock-speed is about 10 times higher. For radio control applications sleeping to save power is not really an option when the model is in motion.
I'm not worried that supplies of the nRF24 are going to dry up next week, but if anyone has suggestions for alternatives I will be interested to consider them.