If the supply of compatible flashcarts ever dries up, it will definitely get harder, though hopefully there will be more software exploits discovered by then.
> The usage of this exploit, regardless of the flashing method, requires access to a small magnet if the target device is of a folding style (any 3DS family system that is not the old 2DS with a sleep switch). This is because the exploit requires your device to enter sleep mode while still having access to the buttons.
another area of research is many flashcarts are actually obfuscation around FPGA and integrated flash perhaps if there was more interest a design could be produced in the spirit of open-hardware sans Nintendo property.
EDIT: I found a recent GBATemp thread where some research into flashcart design is going on. Maybe something will come of that. Link: https://gbatemp.net/threads/gathering-ds-flashcard-knowledge...