Theory checks out. Text of the Constitution is clear. We're not even really talking theory, given that Ford was indeed the only unelected president in our history. He was appointed VP to replace Agnew and succeeded Nixon after his resignation. If there was a plot to put somebody into the presidency and bypass an election, this is the way. Keep in mind the most important part of this: VP appointment requires a MAJORITY approval vote of both Houses of Congress. Relevant to the current makeup, without a VP, there can't be a tiebreaking vote in the Senate. So say Kamala resigned, in theory it could be a deadlock 50-50 for anyone Biden nominated. Important to note that an approval vote by Congress is NOT an "election" as described by the Constitution. The presidential electoral process is spelled out quite clearly. The term limit implemented by the 22nd Amendment clearly states "elected" and thus a person who "becomes" president through appointment and succession is NOT elected. As ready stated, the wordage could have been much simpler: "no person may hold the office of President for more than 2 full terms or a maximum of 10 years" etc. But that's not what the text says. From a textual interpretation, this reading holds water. Even from an originalist interpretation, this ready holds because the original meaning of the word "elected" meant the same as it does now. Perhaps it was not the intent of the Congress to allow for this loop hole, but the 22nd was passed and ratified BEFORE the presidential order of succession was more firmly established in the 25th Amendment. The assumption of the earlier Congress was likely that the original intent of the Framers was to be preserved as far as what was to happen in a presidential vacancy: the VP would become acting president until a new election would be held. Problem is that the text of the Constitution is ambiguous as to whether that meant until the next "scheduled" election or immediate. In all of my study of the Constitutional convention, and history since it, the more correct understanding would be that a new election should be held IMMEDIATELY. The Constitution doesn't say "all presidential elections must occur on this date." It allows for special elections should vacanies occur. Granted, it eventually would be amended to specific term starts and finishes. But that only happened because of the long-standing inconclusive understanding of the text. When John Tyler assumed office, there was debate about whether he became president or was, according to Article II, to "ACT" as President. His party controlled Congress and thus, his move wasn't seriously challenged. Same thing when Johnson succeeded Lincoln. Same with McKinley etc. Sure there was federal statutory law to deal with line of succession past the VP, but that wasn't until 1947 and it still didn't address the issue over "becomes" president or "acts" as president, pending a new election or when such election should occur.

The 25th did remedy much of the issues with presidential succession, but the loophole of the 22nd is still very much legitimate. Granted, I've never been in favor of any kind of term limits as such they violate a person's equal protection right to serve. The Framers had that debate and the prevailing view was no limits. If Washington or Lincoln (or Trump) wanted to serve for life and the people and Electors wanted them to do so, then why not? Why punish the nation to bar a qualified, desired candidate from holding any office? Term limits were built in... they are called ELECTIONS. Of course, this assumes that elections are fair and reliable, which is our actual problem, not the lack of limits. And as for the appointment process, I don't even object to that as it'd still require a vote of Congress to approve. Frankly, direct election of the president, which we basically now have because of the state winner-take-all general ticket method, and illegal constraints denying Electors their constitutional right to vote as independent agents, is stupid and dangerous. At least with a vote of Congress, it'd be in keeping more with the original intent of the Constitution and the Framers. If more people realized the importance of Congress in these processes, maybe they'd give more shits about voting in their local elections as opposed to only caring about the presidential election... but such is the consequence of the expansion of the office and national party politics.