4xcsl, if WXP became successful enough to spin-off in an IPO, it would remain a Wave asset with Wave having her portion of the new shares, while Sarnoff and any other equity holders would have their's.
Any asset Wave holds could increase the WAVX shareholder value. Obviously should a spun-off WXP become a big asset (like Wave's WXP shares worth $100M or whatever) this asset would likely be reflected in the SP of WAVX. I suppose it's also possible that Wave could spin shares of an IPO'ed WXP off to WAVX shareholders. Either way, whether Wave holds the new WXP shares as a Wave asset or spins them off to their shareholders, there would be value to the Wave shareholders, providing of course the WXP shares do well.