So, Marvel got Sony to let Spider-man join the Avengers in future movies. Would be cool if they get FOX to let the use the X-Men and FF for Infinity War.
For anybody wondering when Fox could lose the X-Men rights
The above link is the most detail you are going to get on the 1993 agreement that is publicly available. This is from when Fox sued Marvel over mutant X. The courts discuss the 1993 agreement in ruling on that lawsuit and the implication here is that the rights are indefinite. If there was a time limit on the rights then it would likely have been referenced but the only reference to the rights returning to Marvel is in the event Fox does not produce a film within a set time period.
In October 1993, Fox and Marvel entered into an agreement (the “1993 Agreement” or “Agreement”) pursuant to which Marvel licensed to Fox the exclusive right to create, produce, distribute and market theatrical motion pictures based on the “X-Men Property” (or “Property”), which refers to the “X-Men comic book series.” (1993 Agreement ¶ 6.) The scope of the grant of rights was broad, although the media within which they could be exploited (i.e. theatrical motion pictures) was narrow. Paragraph 6 of the Agreement, entitled “Granted Rights,” states that Property to which Fox obtained rights included (i) certain characters specified in Exhibit A to the Agreement, (ii) the so-called “origin stories” of those characters appearing in the story or screenplay of the film, (iii) all individual storylines from individual comic books other than the origin stories, and, in a catch-all provision, (iv) “all other elements relating to the Property and the Characters.” (Id.) (emphasis added). This paragraph also specifies that the rights “include the right to use the title (or subtitle or portion of the title) of the Property or any component of the Property as the title of any Picture or related exploitation.” (Id.)** In addition to the $1.6 million purchase price, (Declaration of Thomas Rothman dated June 26, 2001 (“Rothman Decl.”) ¶ 10)2, and a percentage of gross proceeds**, (1993 Agreement ¶¶ 4, 5), Marvel was able to reserve, in Paragraph 7 of the Agreement, certain rights for itself in connection with the films to be developed by Fox.3 Other ancillary rights, which define the scope of Fox’s granted rights as applied to other media, are treated in Paragraph 8, the content of which is at the center of the parties’ contractual dispute in this case. Paragraph 8, entitled “Other Rights,” reads in pertinent part:
Marvel reserves all television rights [based on the Property] (other than television rights with respect to the Pictures produced hereunder). However, prior to the reversion (if any) of the Rights … Marvel shall not, without Fox’s prior written consent, which consent may be withheld in Fox’s sole discretion, produce, distribute or exploit or authorize the production, distribution or exploitation of any live-action motion picture for free television exhibition, pay television exhibition, non-theatrical exhibition, or home video exhibition (on cassettes or discs) or any feature-length animated motion picture for non-theatrical exhibition or home video exhibition (on cassettes or discs).4
(1993 Agreement ¶ 8.) The possible reversion of rights to Marvel is addressed in Paragraph 9. In effect, this paragraph sets control dates by which Fox must create sequels by requiring reversion where “Subsequent Pictures” are not made within [155 F.Supp.2d 8] a certain time. (Id. ¶ 9.) The reversion dates set forth in this Paragraph were extended by an amendment to the Agreement signed by the parties on or about October 10, 2000.5 (See “X-Men II” Amendment/Extension ¶ 2(d).)
How Marvel went into Disney
Marvel went into bankruptcy in 1996 and emerged from Bankruptcy in September 1998.