2 passive peers connect over DHT (open port not needed/no advantage)?

[postcd]

Hello,

when i
A) create private torrent
vs
B) create public torrent (DHT enabled)

and 1 active seeder + 2 leechers (passive = have not open port)
The two passive leechers will be unable to connect each other i am guessing.

But main question, if DHT will work, will they be able to connect and upload each to other? At which probability, rough percentage estimate?

Per what i have read, the passives will interconnect only if all following is met:
1) torrent is open, not closed (which means DHT, PEX is enabled)
2) BT client has uTP support (uTP supports NAT traversal/hole punching which is what help interconnect), seems like possibly most client has such support
3) router on both sides has "transparent/p2p friendly" NAT

This article says "This is useful for peers behind a NAT that may not know their external port, and supporting uTP, they accept incoming connections on the same port as the DHT port."
This article says "μTP also adds support for NAT traversal using UDP hole punching between two port-restricted peers where a third unrestricted peer acts as a STUN server." and in referenced post that the uTorrent "implement NAT hole-punching for uTP connections, so connectivity should be improved for peers that do not have their ports mapped."
This article shows that the user enabled uTP in qBittorrent and it made his firewalled torrent client show a green status, not orange one. Green means "better" connection i think?
This article claims that "There's no hole punching that works with all NATs. ... done via an extension to the peer-exchange functionality ... libtorrent
and uTorrent supports this" - so i guess i need to have open torrent in order PEX(and so NAT traversal/hole punching) is working?