The body won't decompose in the same way - because the tissues are being kept oxygenated by the ventilator. There will be degeneration though, you just can't keep a dead body oxygenated in the same way. You can artifically oxygenate the tissues, and provide medication, but you can't replicate the complex hormone/metabolite etc levels required in order to 'live' without some brain function.
Tissue perfusion and viability will become more and more problematic - bedsores will develop and just can't 'heal' in any effective way, the risk of infection will be huge (there is a huge amount of dead tissue). It will become progressively more difficult to maintain patent IV access, which will be vital to keep this 'process' ongoing, in a living patient it is incredibly difficult to maintain IV access and provide nutrition via TPN for any prolonged length of time - in this case, and in the case in Texas you could - possiby could - get weeks but doubtful any longer.