I think Shockwave is going to need much more than a new train though. Seeing that both of the other 1994 major coasters are having large scale track re works. It would be safe to assume that Shockwave will at least need at least some type of track work, as is common with almost every old coaster. Even though it is nothing special, the ride does pull some forces at parts, which will be transferred on to the track and structure. So I think it is much more than just replacing the aging trains.
As far as I am aware, there has not been any substantial track work on the ride to date.
That said, even with it's height requirement, it does fit the top end of the 'family thrill' spectrum I would say. So who knows. Personally, I could not imagine a Drayton without it, it would look weird not seeing that ride at that end of the park.
With some modifications to the ride system, the ride could easily accommodate dual trains. The ride used to run two trains a good few years ago, but I believe they stopped this after The Smiler accident happened as the trains were manually dispatched with no proper block sections.
The ride operates at least 3 block sections. Trains have stopped at the top of the lift hill before, waiting for trains to clear the end brake. (In testing mainly). I am not sure if the transfer and pre lift section is classed as a block. But the lift, main ride, and station are all block sections. Allowing 2 trains to safely run without colliding. You always need 1 more block than the amount of trains you are running. But the ride 100% does use a block section system. The block system also allows a train to be stopped by the main brake, before moving forward into the station but behind the loading section. This would clear the main ride block then allowing a train over the lift hill, before the train has fully parked in the loading platform. Nemesis has a similar setup, just they have a transfer track there instead. As in once the train clears the main stopping brakes, the previous block is considered clear, even though it is not in the station position just yet. So if a train were on Nemesis transfer track section, a train could crest the lift hill - in theory.
By 1994, Intamin and Giovanola were building block sections into pretty much every coaster they built. Especially large coasters like Shockwave.