No one can know in advance whether there will be any further updates after the keyboard is bought never mind how many or what the final one will be .

You buy the instrument for what it is when you buy it . Nobody (as far as I know ) buys an instrument for an agreed price based upon free updates that may or may not happen to emerge at some point in the future with features styles and samples that you may not ever need use or want .

Certainly the korg “ next “ OS was complete unexpected and was never understood to be part of the price when the instrument was bought 4 years ago .

Whatever it cost the manufacturer to produce has absolutely nothing to do with the price buyers /owners paid for or it . I know I did not pay the manufacturers suggested price for mine , or have I got this completely wrong and my years of studying economics , supply and demand price elasticity etc been completely debunked ?