I don't think BJJ has a fan base outside of those who practice it. Even among those who do practice it it has a small fan base.
K-1 and MMA have a fan base outside of those who practice, and ADCC also draws some, but as far as spectator friendliness goes you just need to listen to some Eddie Bravo rants.
Submission Wrestling/Grappling has more potential for excitement because people come from different backgrounds. You'll have wrestlers getting takedowns quite easily against BJJ guys, who will then be getting quick subs. Of course you'll have some weird stuff like wrestlers caught in lockdown and unable to progress because they're moving forwards, and BJJ guys unable to reguard from lockdown because they're moving so far forward and they don't want to give up position either, and unable to sweep because wrestlers don't give up position (I saw this a lot at a FILA Grappling tournament I reffed). At the higher levels this shouldn't be happening. BJJ is more homogenous.
Another advantage of Submission Wrestling/Grappling, is even if it's somewhat vertical, it combines several fan bases. Judoka will watch it for the one or two Judoka competing, wrestlers will watch it for the wrestlers competing, Samboists for the Samboists and BJJers for the BJJers. It'll also draw attention from the MMA fan base (if in the Olympics) because of its similarity in some areas to MMA.
An even better bonus is if FILA Grappling makes it to the Olympics, there's no concern of it watering down any sports. BJJ will be left alone, because it's a separate sport.