Although Microchip has an unusually long commitment to making old micro controllers available, the integrators of them into boards we might use such as the Teensy 2.0 are not required to follow suit.
The first FlexAbility microcontroller boards are based on the later Teensy 3.x series which use newer ARM based designs from Freescale (now owned by NXP).
According to NXP the the KL26 of the Teensy 3 LC will be available until 15 years from time of release back in May 2015.
The Teensy 3.2 uses the MK40 series available until 15 years from release back in July 2011.
The Teensy 3.5/3.6 will be available until 15 years from January 2014 and May 2015 respectively.
PJRC intends to continue production of Teensy 2.0. We have purchases scheduled with Atmel sufficient to keep Teensy 2.0 available until at least April 2021, assuming sales continue at 2017’s rate. This doesn’t necessarily mean we will discontinue Teensy 2.0 in 2021. That’s a decision we’ll consider in late 2020. We understand many people use these older 8 bit products. While we can’t make an absolute gaurantee of future availability, we can tell you we’re planning to continue production of Teensy 2.0.”