A lot of the PM track is over the Subs . . . it would be very expensive to plop down new pylons in this area of the land, and there isn't a lot of space in DL's Tomorrowland for a motorbike coaster, they would have to take out the old double-length people mover track, somehow fit the motorbike Tron coaster, probably a high speed launch and a hair-pin turn at the entrance, but the coaster couldn't go into the buildings like the People Mover (not unless they do a major demolition/construction project, and they'd had to sink new pylons, even then there isn't a whole lot of space.
Innovention's footprint is about 200 feet across, I'd think they need to demolish it and try to build something bigger, but still kinda awkward.
The most workable solution (cheapest) would be to have the motorbike coaster go over the roofs of Tomorrowland, I'd guess they'd have to be themed, but it would allow for turns and an outside portion of the track similar to what is being built for Shanghai.
I kinda think that Shanghai's Tron coaster will be an exclusive for that park for a while. Shendi is pretty secretive/controlling with regards to the project, and they've being studying HKDL and obviously want Shanghai to be the best, and that may well include having exclusive E-Tickets.
You can see why they don't tear down the PM track over the Subs, it might well not need to be removed, and they probably wouldn't put in another track over the Subs, so if they want to put in a ride in this area in the future, might as well keep the old track (or at least the pylons).