I don't think Soundwave needs an alt form directly related to communications. Back in G1 he was pretty much a spy in addition to being their comm officer. So I'd like to see a more devious alt form - like Marine One or something. An EA-6B Prowler would be kinda cool and a tad more fitting with the communications deal, but its being phased out of use and its pretty old. The replacement to that is a slightly modified F/A-18, but even that seems old compared to the F-22s and just not as Soundwave-ish.
Shockwave may as well not have an earth alt, but he should definitely have his cannon mode. Thundercracker could be an F-35 just to differentiate from Starscream (and to sell more/different toys, and give them an opportunity to make his robot form more G1-like), and of course the Constructicons could just be various real machines.
An Army (real) Hummer sounds good for Hound, they could use the new Pontiac G8 for Wheeljack, and a Vette police car for Prowl (Impala police cruiser would be too lame). It would be nice to have some more international brands to use for the Autobots, but there should be enough GMs for a few more appropriate modernizations. They don't need many new Autobots anyway since only Jazz died, and they can bring him back anyway.
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