Warning: As always, do not install this OS if you want to continue using Ndless, even if one day, Ndless ever comes out for OS 4.0.
Texas Instruments will soon make available a new TI-Nspire OS, OS 4.0.3.29. As reported by TI-Planet, this OS offers the following feature: It still fits in the TI-Nspire CX memory. It also comes with Boot2 4.0.3.49, which is where the biggest changes take places it seems. Boot2 4.0.3.49 is 1.25 MB large instead of 1 MB and it comes with Boot1.5, meaning that the Nspire booting process now occurs in 4 steps rather than three. Could this be a new security measure? Or is it simply to protect the calculator against bricking more? In any case, it will most likely not support Ndless for months.
Source:
https://tiplanet.org/forum/viewtopic.php?p=192776#p192776
https://tiplanet.org/forum/viewtopic.php?p=192841#p192841