Back in September 2020, Microsoft announced that the next version of Exchange Server would land in the second half of 2021. However, the company missed this deadline due to a global onslaught on on-premises Exchange servers from malicious actors. With Microsoft re-prioritizing to focus on Exchange security, it has now announced that the next version of Exchange Server will launch in the second half of 2025 - which is a four-year delay compared to its initial strategy.
The next version of Exchange Server (let's refer to it as "Exchange Server 2025" for simplicity throughout the rest of this article) will be available only to customers with Software Assurance. It will also require a Server and Client Access License (CAL). Although we know that it will be available via a subscription model, Microsoft says that it will share more details about pricing, features, branding, and requirements in the first half of 2024.
As ZDNet's Mary Jo Foley points out, Exchange Server 2016 and 2019 will be supported until October 14, 2025, but only Exchange Server 2025 will be supported after that date. Interestingly, this version of Exchange Server will have no end of support date and Microsoft will continue to support it until there is "substantive market demand".
Microsoft has also hinted that it is working on in-place upgrades for those on Exchange Server 2019. This indicates that you might not need new hardware or plan mailbox migrations when updating to Exchange Server 2025.
In the meantime, Microsoft has highlighted a bunch of improvements and features that it has introduced to Exchange Server 2019, which will continue to be its latest release for at least the next three years. You can check out the recent advancements in Exchange Server 2019 in Microsoft's blog post here.