Some of those big software platforms will never be FOSS. You are never going to see a FOSS CADD package that is equivalent to AutoCAD, Microstation or the other major players. This is software that requires thousands of man hours just to keep up with the innovation in the field and that means commercial vendors with pricey support contracts to move the software along.
Having tried every FOSS CADD package a couple years ago I can say with certainty there wasn't a single one that was even close to the cheapest 2D piece of crap commercial software in existence (there are 4th tier commercial indie CAD applications that are available for near nothing that are better than QCAD which was the best I tried) let alone offered real 3D and the precision necessary in commercial engineering.
If Linux is to succeed commercially we need commercial software. There is a lot of software that is only going to be developed as commercial software because of the specialization and work involved.