I think Blender's "threat" to the pro market is dramatically overstated.  I tried Blender recently, and it's not even close to a 1:1 feature comparison to 3dsmax's current state, even with the lagging dev of Max in the past couple upgrades.  I'm assuming the same is true with Maya.  I imagine it would take Blender to possibly a ver 3.0 before it will have a comparible feature set to either Max or Maya (can't speak to C4D), and by that time, both of those apps will have been developed further as well.

I look at Blender's presence in the 3D app market like POV-Ray's in the rendering market.  POV is a great render engine, with tons of great features, but never became a go-to rendering software in the professional industry.  It never overtook Vray, or some of the others, and while it boasts a very impressive model description language, it most likely will never develop to the point to put any of the commercial competitors out of business.

Blender is great, but not likely the threat to Autodesk's products that the open-source community is hoping for, and even mid-range apps like Carrara arent in that much danger.  Most of Carrara's user base seems to be hobbyist, to intermediate 3D enthusiasts, and my opinion is that Blender is in a strange area where it will probably never fully surpass the functionality of Max or Maya, but is still way too complicated and complex for the average hobbyist looking to compliment Poser.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.