I don't think it would have been good for East-west relations or the Kohl government, but it might have averted some long-term nastiness. Of course neither the East German nor the West German government wanted this - Kohl was a German patriot who wanted reunification now, complete and final. de Maiziere was elected largely on the promise of reunification, through the support of Kohl's CDU. A lot of Easat Germans understood very well that they were in for trouble and preferreed to have the Wessis in the boat to share it.
Yor only realistic chance the way I see it is for the allied governments to put the brakes on. The immediate effect would be unpleasant - lots of frustration in East and West Germany. The East German government would find itself with a mission they didn't want or campaign for while the West would be embarrassed by its inability to get things done. Quite a few perople would openly ask why we are in NATO if we can't trust our putative friends. West germans would go East as advisers, entrepreneurs and to render aid, of course, but that could easily become a fraught relationship. Without unification, the Mark Ost is going to collapse, and pumping in aid will only perpetuate inefficiencies. There is no way an independent GDR will agree to restitution or the dismantling of its industry. West Germnans could in a few short years come to even more deeply resent competition from cheap labour. By the time unification is made possiblem it may not get a secure majority any more (and you can't really do that kind of thing without a solid popular mandate).
Economically, it would probably be a good thing, actually. Unification was an unalloyed disaster. Without the inflationary boost of the 'currency union' bribe, Europe and especially West Germany might be spared the phase of sky-high interest rates that kept the deutschmark from crashing. The German welfare state would remain solvent longer without the entry of huge numbers of people who had never contributed to the funds, but now had greatly inflated claims earned in a weaker currency, but due in a strong one. Unemployment in the east would peak earlier and lower without destroying its last vestiges of competitiveness through introducing the deutschmark and investment would find a readier home without the threat of restitution hanging over every property. Also, if the Ossis get around to any kind of Truth and Reconciliation business, there won't be the ready excuse that it's victors' justice.
The problem is that no voter ever professed gratitude for less pain than there could have been. The East would still be materially worse off, and likely resentful for it, the West better off, but resentful of the perceived ingratitude of the East and the obstructiveness of the allies.