Wiliam,
Oil prices are driven by market supply and demand forces, not the whim of the Middle Eastern producers. We have high oil prices now because of increasing demand from China and Asia for oil but there's correspondingly less oil being produced to meet that demand...mostly because the current exporters are producing at or near capacity already. It's not in their longterm interest to see high oil prices as that actually reduced consumption and their profit/revenue flows.
Anyhow, back to the topic of the future of the MBT...I do think we are a pivotal moment in terms of where technology and strategic needs play a role. The MBT is taking on a lot of the characteristics that battleships had at the start of WWII. They are expensive, highly visible expressions of force/might, but really only useful if the other guy also has expensive highly visible expressions of force/might for them to go up against and defeat.
I think there is still a place for the Abrams in the TO&E of the modern army but it's role is diminishing as more and more conflicts become localized or asymmetrical as opposed to the mass battles on the plains of Central Europe that were once envisaged. Smally unit mobility and survivability are coming more to the forefront and the role of the MBT by contrast is being reduced to the background.