1. England
Jofra Archer. The Rajasthan Royals pacer had surgery on his elbow and he is racing against time to be fit even for the Ashes in November. It is unlikely that ECB would want to him to be rushed for the IPL 2021. Injured Ben Stokes of RR, Eoin Morgan, the KKR captain, Jos Buttler, the RR opener, Sam Billings, the Delhi Capitals player, Sam Curran, the Chennai Super Kings all-rounder, Dawid Malan, the Punjab Kings batsman, Jonny Bairstow, the SRH batsman, etc all are integral part of England white ball scheme of things. Considering the Bangladesh tour and T20 WC, they might be told to abstain from IPL 2021. Moeen Ali, the CSK all-rounder, might just turn up as he is currently out of favour in England white-ball set up.
2. Australia
Pat Cummins of Kolkata Knight Riders is in doubt for IPL 2021. Similarly, David Warner of Sunrisers Hyderabad, Steve Smith of Delhi Capitals and Daniel Sams and Glenn Maxwell of Royal Challengers Bangalore, all could miss the remainder of the IPL. None of them - barring Maxwell - are travelling to the West Indies for a limited-over series in July followed by a tour to Bangladesh because of bubble fatigue. Though the Aussies do not have any international commitments during the IPL 2021 window, they would like to be with their families because of the T20 World Cup and the Ashes. They also have spent considerable time inside the bio-bubble. A final call might be taken in July after the series against West Indies.
3. New Zealand
Kane Williamson (Sunrisers Hyderabad), Kyle Jamieson (RCB), Trent Boult (Mumbai Indians), Tim Seifert (KKR), Mitchell Santner (CSK), are some of the frontline New Zealand players in the IPL 2021. We may not see many of them returning for the remaining IPL matches in the UAE. There will be tour to Bangladesh in August and they also have to keep in mind that there will be a T20 World Cup and a Test series against Australia later in the year. The NZC would not want to place undue stress on the players in that scenario.
4. West Indies
Kieron Pollard (Mumbai Indians), Shimron Hetmyer (Delhi Capitals), Jason Holder (SRH), Andre Russell, Sunil Narine (KKR), Chris Gayle, Nicholas Pooran (Punjab Kings) Dwayne Bravo (CSK) etc are the main West Indian representation in the IPL 2021. But they are also signed for the Caribbean Premier League (CPL 2021) and it ends just four days ahead of the IPL. There were talks about BCCI approaching CWI to advance the CPL by a week or 10 days so that the players have enough time for the bubble-to-bubble transfer. However, nothing has been official yet. In that context, a few of them might just stay away especially those who are a part of the Windies team like Holder, Russell and Pollard.