I am guessing they will implement a 'pledge' system of their own. Have people pledge on you (which they take say 10%, similar to patreon) and maybe add the subs and viewers bonus on top. As much as I love webtoon I always wonder how they actually have revenue. There is no high amount of ads, no merch, no 'premium' comics...just some ads at the end of a comic sometimes.
When your growth is high, you do need to make a way to generated revenue to keep going, so them implementing a 'patreon' like system that they own seems logical.