More than half of the current starting grid will be out of contract at the end of the season but inevitably some stand out more than others.
Several potential candidates are not even in Formula One at present and look like long-shots, but Formula One is never short of surprises.
The following looks at the possible options for Mercedes and the questions raised.
CARLOS SAINZ, 29
The Spaniard whose place has been taken by Hamilton would be a straight swap. He has, however, been considered a top target for Audi, who are taking over Sauber and entering as a works team in 2026. He would be the likely number one there, and Audi have strong connections with his father who won last month's Dakar Rally with them. Would either he or Mercedes want to do a deal for one year or would he be open to a longer one?
ALEX ALBON, 27
The ex-Red Bull driver has been a big hit with Mercedes-powered Williams, scoring all but one of their points last season and hauling them up to seventh overall. Williams are run by James Vowles, who was previously a close confidant of Mercedes principal Toto Wolff as that team's head of motorsport strategy. A deal for Albon, an old friend and rival of George Russell who also graduated from Williams, would surely be straightforward.
ANDREA KIMI ANTONELLI, 17
The 17-year-old Italian is yet to debut in Formula Two but considered a big talent for the future and already under contract to Mercedes. If not ready for the former champions, he might be offered to Williams to get experience.
MICK SCHUMACHER, 24
Michael Schumacher's son is the official reserve. His seasons with Haas were difficult and he is now on the roster of endurance drivers with Renault-owned Alpine. Michael raced for the team, his place taken by Hamilton in 2013, but Mick looks a long shot compared to other options.
ESTEBAN OCON, 27
A Mercedes-backed junior driver and reserve and preparing for his eighth season in F1 and fifth with Renault/Alpine. The team rated him very highly but he may have slipped down the list of options by now.
VALTTERI BOTTAS, 34
Hamilton's team mate before Russell replaced the Finn, who will be out of contract at Sauber at the end of the year and whose place could go to Sainz. He knows all the people at Mercedes but a return would surely be unlikely.
FERNANDO ALONSO, 42
The evergreen double world champion is out of contract at Aston Martin at the end of the year but showing no sign of wanting to stop and still looking highly competitive.
SEBASTIAN VETTEL, 36
Could Germany's four-times world champion be persuaded to come out of retirement and make a comeback, just as Schumacher did in 2010? Vettel, at 36, is younger than Hamilton. He didn't entirely rule out a return when he left Aston Martin in 2022.
