This release of Windows 10 Enterprise Technical Preview Build 10061 seems to run the 'old' WinPcap just fine. Whatever was broken in 10041 was fixed - I wonder: was NDIS backwards compatibility restored? I don't know, but it works. At least for now. With the rumored final Windows 10 release coming in July 2015, things had better start to get finalized soon. That means networking too.
So for now, Windows 10 build 10061, seems to capture packets fine with Wireshark 1.12.4 and old 4.1.3 WinPcap release. WinPcap also sends customized packets correctly from NetScanTools Pro v11. We'll see what the next build does.
Update June 5, 2015: WinPcap 4.1.3 also runs on build 10130.