On PS4 1st or 2nd year digital ratio was lower than 25% as far as I remember.
Yeah, there were changes in the last year and it seems about right that Nintendo is a few years behind the pack regarding digital. This all looks more or less plausible.
The only thing we don't know is if Switch will follow a trend "launch aligned" to reach 50% as the table consoles or if people when weighting pros and cons of portability on digital versus HDD size will decide for not going 50%+
For someone that plays 2-3 games at a time I don't think HDD size is a major problem if it's fast to download or keep backup in an external HDD or PC (that you need to validate before transfer to Switch internal memory), and for sure it is better to have all the games you need already in the system without needing to carry extra disks.
Myself because of collection and liking to pay less on older titles that I didn't want to pay day one 60 USD will still majorly physical, but I can see Switch userbase going more and more digital.