Husserl is always criticized for reifying the transcendental ego and placing it "outside history," and it's often said or implied that Heidegger's hermeneuticizing and historicizing of Husserl's "Cartesian," ahistorical phenomenology was the necessary next step. The basic idea seems to be that Husserl treated the subject and its a priori configuration as a being (or beings), and Heidegger came along and posited fully immanent Being as the condition of ALL beings, including consciousness, the ego, subjectivity, etc.
But how is Dasein/Being not itself treated as a being in Heidegger? How is his phenomenology not just as ahistorical? This was Derrida's critique, and Leo Strauss' critique as well. If Heidegger is truly consistent, then he can't even keep "Being," since then he has to historicize everything, including his own ideas of Dasein with its clearings, disclosures, aletheias, and so on. But then you end up in "therapeutic" linguistic philosophies like Derrida or Wittgenstein, which are (Strauss says) simply nihilistic, they are merely ancient scepticism rehashed. Or if you follow Strauss, you end up actually going back to something closer to what Husserl wanted, which is the open acknowledgment that there may be real essences grounding thought/being, whether platonically or transcendentally real, and the attempt to grasp or approach these essences.
How would Heidegger have answered this? I know that a Derridean neoliberal yuppie piece of shit would simply tell me to embrace his therapeutic sceptico-nihilism. And I know that a Straussian would tell me to become a Jew living in New York or Chicago in the 1950s. But how would HEIDEGGER have answered? Clearly he didn't take himself to be a Husserlian, but surely he was smart enough to understand the stakes of reifying Being as an atemporal potentiality always supra-historically "available" to any culture? What were Heidegger's real metaphysical beliefs?