Some age numbers for you:
Pat Sajak was 35 when he took over daytime Wheel of Fortune in the infamous "Woolery left Wheel" saga of Christmas 1981, and was not quite 37 when the Wheel went nighttime a couple of years later. He's now 60.
Vanna White was 25 when she took Susan Stafford's place next to the puzzle board in Nov. 1982. She is now 50.
Alex Trebek was 44 when he began his run as host of Jeopardy. He's now 67.
As for each show's announcers, Wheel's Charlie O. will be 75 soon, while Jeopardy!'s Johnny Gilbert is 73, so if those two are still around at their ages, maybe Pat, Vanna and Alex are each good for another decade.
But if there's pressure, be it from advertisers or stations, to retire Pat, Vanna and/or Alex, who would be their replacements?
Pat Kiernan would make a great Jeopardy! host, and maybe also Todd Newton on Wheel now that he was passed up for Drew Carey on TPiR, but both are in, or close to, their late 30's, so would they be too old already if either were to be offered that chance?
And what about Roger Lodge from GSN's Camouflage, who's probably about as old as Todd or P.K., or maybe Jeff Probst of Survivor and R&R J!, never mind that he's not yet 45? Ryan Seacrest of American Idol, given his game show hosting experience pre-Idol, could be an outside shot at age 32, or if that Temptation guy, Rossi Moreale, can prove himself, he might be given either of those.
Oh, and as for that Vanna slot on Wheel? I can't quite take a guess, but if she's not L. Lohan, B. Spears, P. Hilton or N. Richie, I would be happy with that.
Given that Wheel and J! are both well-established with long-term syndication deals into the next decade, I wouldn't see any changes being made--barring the unexpected. But I thought I'd bring up the "what if" on that.