Just before the start of the Christmas buying season Microsoft introduced a new entry level Surface Pro 4 to the Australian and New Zealand markets. The 'unbundle' amounted to the entry level Intel Core m3 version of the SP4 minus the Surface Pen.
The new package was offered at a very good price in the run up to Christmas, usually retailing for 40% less than the regular SP4 m3. Even allowing for the need to buy a Surface Pen and/or Type Cover, that was still something of a bargain.
Anecdotally I heard from several retailers that interest in the SP4 had blown through the roof as a result.
Why so successful? I suspect that a large number of Surface 3 and SP3 owners saw the opportunity of a cheap upgrade. Either selling on their older tablet or repurposing it as a static machine with a cheap keyboard, mouse and display.
Why such a good deal on the m3 version of the SP4? It's likely the least popular model in the standard SP4 pricing model, despite its fanless design. If you're buying an SP4 chances are you'd spend a little more to get a higher spec option.
With the SP5 surely not too far away, carrying stocks of the m3 version was probably too big a risk given the potential for an ARM powered variant making the m3 obsolete.