Because I don’t know approximately what the future of phones will hold, I cannot comment intelligently on the long-term future of Apple into 2024 and beyond. However, I can comment on what the U.S. tax system and Apple’s new commitment to financial engineering (through stock buybacks) have done to the company’s balance sheet.
One of the very many peculiarities of our tax system is that companies domiciled in the United States have to pay a repatriation tax to bring money generated outside the U.S. back to American coffers. If a corporation files a form indicating that the money will be kept permanently overseas, then there is no tax. If the money is bought back home, there is a 35% tax applied to the income. If you’re ExxonMobil, this is what the incentive picture looks like to you: You generate $100 million in profits in Brazil. You can (1) bring that money back to the United States to pay dividends, repurchase stock, or drill new oil fields, but you will only have $65 million to deploy after paying the U.S. federal government for the right to transfer that money from Brazilian banks to American banks. OR (2) you can permanently reinvest that $100 million into new Brazilian growth prospects, and Uncle Sam will get 0%.