Good job, I noticed few things.
To ATi should be added Rage II+ (without DVD). Rage LT Pro and XL/XC are from Rage Pro, so they should have branch left of Rage 128. And VT4 should imo continue Rage II line rather then VT2.
Virge MX should be connected to GX2.
Matrox M-Series and APVe should be added and Mpact /3600 from 1997 and Glint 300TX.
Not sure why you have different capacities for Permedia 2 and 2V. Glint R3 is the chip of Permedia 3, isn't it?
Cyberblade XP arrived in 2001.
Banshee. And Velocity was so awesome it spilled into retail.
Glint 300TX - planned but probably never realeased, they did 500TX instead - at last i haven't found single card with 300TX or any article about it.
Permedia 3 and Glint R3 - dont know, Glint R3 is earlier and was used on Oxygen VX1 card. Permedia 3 Create should have Permedia 3 chipset, but dunno if they're the same or not.
different capacities for Permedia 2 and 2V - no info about 2V version - probably die shrink only, but never seen 2V card with more than 4MB
Mpact /3600 - is unclear - there should be 2 different clocked versions, but there are 3 makers of this chip and not sure if someone made slower versions, so i just used Mpact for both clocked variants.
Cyberblade XP - freelibrary says second half of 2000 - see
here
Matrox M-Series - aren't they using P690 chipset?
Rage II+ never seen one without DVD after +, they spoke about it, but not sure if they ever made one without dvd. Need photo.
And VT4 should imo continue Rage II line rather then VT2 - VT4 have 3d capabilities? Thought that its only 2d card like VT2.
Rage LT Pro and XL/XC are from Rage Pro - Rage LT Pro comes from Rage LT since its evolution of this chipset and its mobile branch - if i link it to Rage Pro, then i should link every mobile chipset to desktop variants and for that theres not enough space. So i just branch 1st mobile version and then use all never chipsets only in mobile tree.
XL/XC are from Rage Pro - fixed
Virge MX should be connected to GX2 - fixed
Branching worked only before too many cards were released, at later year i gave up and split cards into highend/middle and lowend ones, sometimes i used other branch when out of space.