If I understand this correctly, they'll be able to write their own checks because they will essentially...
1) Own self-driving and thus, most personal transportation
3) Own / replace a large segment of public utility / power companies
4) Own / replace a large segment of insurance
5) Own / replace transportation power network
Right now, it's silly to think of Tesla as some kind of mega-monopoly across industries. So we invest in them betting on them becoming that. Is that what we want?
My counter-argument is that one of the bigger markets for automobiles, the U.S., is designed around personal choice, personal autonomy, etc. Many people just want a working car to give them freedom, and will buy whatever popular, trusted brand is available. The rest want one of the smaller brands, something that seems different from the mainstream (even if it's really barely skin deep). That has kept quite a few big players in the automotive marketplace, and despite consolidation over time, there's still variety, which buyers want. This argument really only addresses them as a car maker, though... and not at all for their spread across industry lines.