I think any relaunch should be headlined with a Surface device, definitely a hero device that shows everything that Windows is capable of.
Even if this is accompanied by lower-end devices, there has to be a Surface device leading the relaunch and let's not make any mistakes, this will definitely be a relaunch of the Windows brand on phones.
As for the Lumia brand, I think it's dead and should be dropped. While anyone I know who has ever used a Lumia device, including people who use Android and iPhone in their daily lives, have been impressed with the phones when being issued them for work, the wider impression is that Lumia is failed and as long as MS keeps naming their devices with that moniker, the devices will be considered to be part of a failed ecosystem.