You're going off on a tangent here. Only you raise the prospect of breaking anything for the Arduino IDE! Not proposed/desired.I have no intention of making sacrifices on people's experience with the Arduino IDE, especially with regard to the many libraries designed for AVR chips which do indeed work perfectly on Teensy LC & 3.1.
Editing the boards.txt file is useful. But what's needed is for VM with the latest non-beta Arduino to work with Tim's instructions for installation. Like VM did before 1.6 and the restructuring of T3 core to be subordinated under the AVR directory tree - which Tim said was is reluctance to continue supporting T3. I did find a way to cope with this and passed it on to people here. But this is a band-aid and is disjoint from VM's good user support, easy installation for the novices, as seen on the VM forum and web site.