I’ve learnt from grammar books that möchten is mögen in subjunctive 2. I would like to use it but together with werden. Is it possible?
Ich möchte es lesen.
Ich werde es lesen möchten.
Your grammar book is correct: möchten is not a verb of its own right, it is simply an inflected form of mögen. Thus, taking it into any case other then present you must use a corresponding form of mögen:
Ich möchte ein Brot.
Ich mochte ein Brot.
Ich habe ein Brot gemocht.
Ich werde ein Brot mögen.
Ich werde ein Brot gemocht haben.
However note two things:
It is very uncommon to use future tense in German in everyday language. In almost all cases, present tense is used instead.
Morgen möchte ich ein Brot.
Since using the form möchte is directly requesting something, it sounds weird to my ears putting it into any other tense. The requesting sense of möchte overlaps too strongly with the full verb mögen in its to want meaning, so I am much more inclined to understand those sentences as ‘I wanted; I will want; I will have wanted’ without the intrinsic politeness of möchte.
Subjunctive, as described in grammar books is rarely used in everyday-German. Everybody who reads »Ich möchte es lesen« will understand this sentence as indicative in presence tense: A German native speaker understand this sentence as »I (really) want to read it«, not as »I would read it (if something happens)«
To really show the subjunctive use, you have to construct sentences like this:
Ich möchte es lesen: Wäre das Buch von einem anderen Autor, so möchte ich es lesen.
compare with this similar construction:
Ich stürbe daran: Wäre ich noch lebendig, so stürbe ich bald durch deines Bogens schnellen Pfeil.
When used in Futur I, you don't decline the full verb, but the auxiliary verb. And even more important: You use the infinite form as full verb, which in the case of »möchten« is »mögen«:
Indikativ: Morgen werde ich es mögen.
Konjunktiv II: Morgen würde ich es mögen.
Indikativ: Morgen werde ich sterben.
Konjunktiv II: Morgen würde ich sterben.
As you write,
is Konjunktiv 2 of
It is often used as a more polite substitute for
In that case it will be perceived as a verb of its own in Indikitav Präsens (like will) by many speakers. However this verb (which, as we just saw, does not really exist) is lacking any forms that are not Indikativ Präsens, in particular it has no infinitive möchten. (I remember that this has been discussed here before, with not everyone agreeing to which extent this is still true for colloquial German.) Since it has no infinitive, you cannot use it in Futur, and you will have to replace it with another verb, such as wollen.
Ich werde es lesen wollen.
In most cases it will not be necessary to modify this to make it more polite, since a future desire is less likely to be interpreted as a demand than a present one. On the other hand, it may also be possible to just leave it as
Ich möchte es lesen.
since this already expresses your wish for a future action, and you can modify it by adding when you would like to read it.
Ich möchte es nächstes Jahr lesen.
This would only be wrong if you currently do not feel inclined to read it later but expect to develop a desire to read it at a later time.
No. This doesn't work, as werden can't govern Konjunktiv II. Actually, no auxiliary verb can govern Konjunktiv II, instead, any auxiliary verb will be put into Konjunktiv II instead. So it should be:
However, two things have to be taken into account: würde may have temporal meaning in some cases, but often it is just used as an analytical replacement for synthetic Konjunktiv II. Apart from that, möchten is not understood as Konjunktiv II of mögen anymore. So (2) is neither (1) in the future or identical to (1) in terms of Konjunktiv II.
I don't see a problem with
Ich werde es lesen mögen.
other than that it doesn't make a whole lot of sense. This would imply that you don't want to read it at the moment but you know you will want to read it in the future. Grammatically correct though.