So far, not only did Tim Cook live up to the expectations in Apple under Jobs (which would mean to keep the company value at the same level) but he even overperformed 100%.
Market valuation does not indicate anything about the inner workings of a company, nor about its long-term prospects.
Mediocrity can easily sustain Apple on Wall Street for the next 10 years.
The true measure of the post-Jobs era will be when they will run out of that inertia and will be on their own. Which seems to be happening around these days.
Many tech and near-tech companies doubled and even tripled in value since 2011.