They have a custom coaster section - so they will build you whatever you like.
That said, they weren't really selling many (if any) boomerangs anyway. There are so many of them at various parks, and some that have been removed and put in storage, that it is cheaper to buy one second-hand from another park or for a chain like Six Flags to move them between parks.
But here's some possible reasons for why they wouldn't be making them anymore:
Vekoma is now owned by S&S Worldwide - who produce 4D Freespins, El-Locos, and other Small Footprint launch coasters that are more exciting, smoother, and more popular than boomerangs.
Most of the images on the website seem to indicate that Vekoma is abandoning the Arrow-style track design (wheels running inside the track like on SLCs and boomerangs) in favour of their new track design that makes better track profiling possible for a smoother ride and more exciting elements. The exception appears to be Mine Train coasters, but they have a different track design anyway.
Offering new rides using the new track design means culling old designs that might be cheaper. If you want to sell a more expensive (but better) product, you simply stop offering an cheaper alternative. This also streamlines fabrication by focusing on one style of track and train.
Vekoma seem to be targeting a 'mid-thrill' market rather than trying to out-thrill their competitors. Fun, family-style rides with a couple of 'thrill' elements that Parents and Tweens/teens can enjoy together. This is something that a lot of parks in Asia will be wanting.
These reasons might be completely correct or completely wrong. It's just speculative reasoning on my part.
But personally, I'm excited to see some new designs and better technology from Vekoma. They've been installing the same painful coasters all over the world for decades and trying to 'fix' them with new train designs, while companies like Gerstlauer and Mack eclipsed them on almost every front.
I think some of these new rides would be a great fit for parks like Dreamworld and Sea World. Dreamworld could create an 'aviation' themed area with a flying coaster, the iRide and Tailspin. Sea World is not a 'thrill' park, so Thunderbird model would be a great fit (especially if MW removes AA in the coming years).