The new client will be a cross-platform application.
Microsoft is closing the London office that was home to part of its Skype development, causing the loss of 220 jobs. A further 300 people are losing their jobs in Redmond as Microsoft makes cuts that were previously announced in July. In a statement, the company said:

Microsoft is consolidating offices across London, moving employees to Microsoft’s new office at Paddington. As part of this effort, Microsoft reviewed some London-based roles and made the decision to unify some engineering positions, potentially putting at risk a number of globally focused Skype and Yammer roles. We are deeply committed to doing everything we can to help those impacted through this process. Microsoft will be entering into a consultation process and offer new opportunities, where possible.

Sources close to the matter tell us that another factor may have been influential in the decision to shut down the London Skype office. Currently, the company has the traditional Windows desktop app; the new Universal Windows Platform app for Windows 10, Windows 10 Mobile, Xbox, and Skype; the Skype Web client; and a Web-based standalone app for Linux (which apparently also has internal builds that run on Windows, too). Skype also has mobile apps for iOS and Android in addition to a macOS client.

This is an excessive number of clients, and what we're hearing is that Microsoft's solution is to develop yet another client, codenamed "Skype for Life." This one client will be cross-platform, covering not just Windows but Linux, macOS, iOS, and Android.

The new client, along with Skype for Business (formerly Lynx) and the new Slack-like Skype Teams feature that's being developed, is being built at the company's headquarters in Redmond. With this client being the primary focus, other clients are moving into maintenance mode, making the teams that build them, including many of Skype's London staff, redundant.

Moving Skype development to the US also demonstrates Microsoft's continued change of attitude toward Skype. When Microsoft bought Skype for $8.5 billion in 2011, the company said that it would run the communications firm as its own independent division, leaving Skype management substantially in place. The intent was to avoid a painful and destructive integration effort of the kind that destroyed smartphone company Danger. That approach has now been fully reversed, with major development now occurring stateside. A former employee told the Financial Times that "one of the things that was always a big issue for Microsoft was that big decisions at Skype would usually always be made in Europe, not in Redmond. Now, it’s a Microsoft-led company rather than an independent Skype."