It since ever merely unlikely that many find lineage and liberation, but not impossible, having the "luck" coming in contact.
In fact, the Buddha said, "Be ye lamps unto yourselves." Is this not what he meant?
The Buddha said that to those having already changed to the "lineage" of the Noble Ones, not at all and never to wordilings.
In fact (the act of) the Buddha did not uphold something more importand outwardly as the teacher/admirable friend and pointed strongly on the ancestorship of the lineage:
It is in dependence on me as an admirable friend that beings subject to birth have gained release from birth, that beings subject to aging have gained release from aging, that beings subject to death have gained release from death, that beings subject to sorrow, lamentation, pain, distress, & despair have gained release from sorrow, lamentation, pain, distress, & despair. It is through this line of reasoning that one may know how having admirable friendship, admirable companionship, admirable camaraderie is actually the whole of the holy life."
— SN 45.2
This heritage, to keep it alive, he gave to the Sangha of his disciples, his monks.
Such as Gurus and people outside of the Sangha, especially under lay people, even to draw such as "lineage", is neither given by the teacher nor in any way able to transmit the good Dhamma by nature.
Also that there is such as permission invented in this lineage to teach, is a trader invented mythos, selling pride and identification to merely fools.
Such is pure business and livelihood on Dhamma of which the Buddha put a lot of means into to avoid it.
How ever, "lineage" or better "ancestorship" o the Noble Ones is not gained by birth or outwardly signs and affiliation but by the first stage of awakening, by gaining gotrabhū-ñāṇaṃ
From this moment on, and only from here, one can regard him/herself being talked to when spoken: "make you self an island with the Dhamma (you already have really gained)"
the beginning of lineage...And while this explanation was being given, there arose to Ven. Kondañña the dustless, stainless Dhamma eye—...
...Then ..., having seen the Dhamma, having attained the Dhamma, having known the Dhamma, having fathomed the Dhamma, having crossed over and beyond uncertainty, having no more perplexity, having gained fearlessness, independence of others with regard to the Teacher’s message, ...
While it's not the most bad idea to turn away from Dhamma-dealers and "pyramid-trade" systems, is not smart to turn away from the most needed refuge to stay and have contact with the others, the Sangha.
As maybe observed, there is no such as a formal and regulated disciple-student relation between the members and the Sangha given, as such would neither work, or as we might have faced, leads to very problematic situations. So the relation, aside of natural laws, between lay people and Monks is a total voluntery one, purely based on goodness and generosity, without any formal personal duties.
As it is thought, this field of merits, can possible stay an independent source of teachers of the good Dhamma, others then later developments, copies and thieves for livelyhoods.
On the other hand, by person has not that much doubt that the Juwels, beginning with the Savaka Sangha, will fast disappear in the modern world and not even imagenable for the modern people. That's nature of modern (followed after by many).
Try to be wise and uproot the cause of incapacity of devotion and being capable to be tamed, you ego-tripps.
There would be just immense suffering able to teach you but possible no more refuge avaliable.
Good advices how to find oes good tracher are found in the essay: The Power of Judgment.
More on the topic student teacher relation might be found by one here: [Q&A] Proper way to ask a teacher to become their student
[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]