Non-antiPossible anti-roadblock: Side-skirt the 22nd Amendment.
This would try enacting Woodrow Wilson's bizarre scheme in 1916 should Wilson have not been elected to a second term. (He was narrowly reelected in the Electoral College so the scheme was never put into play.) The issue at hand back then was the very long lame duck session between the November election and the March 4 presidential transition. In case Wilson's opponent had won the election, the plan was to appoint Charles Evans Hughes (Wilson's opponent) as US Secretary of State (second in line back then) and then Wilson and Marshall resigning for Hughes to become acting president until becoming the actual president on March 4th. The modern equivalent would be for Mike Johnson (or whoever is speaker in 2028) to resign as Speaker of the House, the House electing Donald Trump as Speaker, and then Trump and Vance resigning.
HoweverThe validity of such a scheme is not certain, because holding an office that is part of the presidential line of succession does not override the constitutional requirements for being president: age, US citizenship at birth, not having done more than 1 and a half terms already, and so on. In fact, during the Trump and Obama administrations, there have been several example of Secretaries of various Departments being legitimate, Senate-confirmed holders of those offices, and yet not part of the presidential line of succession due, mostly, not to have been born US citizen. Forexamples : for instance, Elaine Chao, Secretary of Transportations under Trump (also known for being Mitch McConnell's wife) was born in Taiwan and excluded from the line of succession during her tenure. So, inIn the scenarioscheme described above, if Trump as Speaker of the House woulddoes not qualify to be acting president, and as specified in 3 USC 19 (b), that duty would fall upon the next person in line, presumably the president pro tempore of the Senate.
However, it is not clear whether having completed 2 terms (or one and one half...) constitutes a bar for being president or acting president, because the wording of the 22nd Amendment specifically bars someone from being "elected" president more than twice. As opposed to the other qualifications of ArtII.S1.C5.1 which mention "be eligible to the Office of President", and the wording of the 14th amendment which mentions "hold any office [] under the United States". Depending on the judge and the court, it may or may not hold.
Anti-roadblock #1#2: Repeal the 22nd Amendment.
If this gets done in time, easy-peasy; there's no longer a bar on becoming a third term President. This has come up before, almost every time the US has had a two term President since FDR. However, none of those repeal proposals had any legs.
Anti-roadblock #2#3: Repeal and replace the entire Constitution.
This, too, is a highly unlikely proposition. However, it has happened in other countries, so while highly unlikely, it is possible.