It has never been Church discipline until recently that non-Catholics can receive communion. Where has the Church taught as doctrine that this can only be done in very grace situations?
Only members of the Orthodox Church may receive Communion (other than in very grave situations).
Canon 844.1 “Catholic ministers may lawfully administer the sacraments only to Catholic members of Christ’s faithful, who equally may lawfully receive them only from Catholic ministers”
The only exceptions to this in Church law are:
Canon 844.3 “Catholic ministers may licitly administer the sacraments of penance, Eucharist and anointing of the sick to members of the oriental churches which do not have full Communion with the Catholic Church, if they ask on their own for the sacraments and are properly disposed. This holds also for members of other churches, which in the judgment of the Apostolic See are in the same condition as the oriental churches as far as these sacraments are concerned”
Non-Catholics (with the exception of members of the Orthodox Church) can only receive Communion in extremely rare situations.
Canon 844.4 “If the danger of death is present or other grave necessity, in the judgment of the diocesan bishop or the conference of bishops, Catholic ministers may licitly administer these sacraments to other Christians who do not have full Communion with the Catholic Church, who cannot approach a minister of their own community and on their own ask for it, provided they manifest Catholic faith in these sacraments and are properly disposed”
So no, Church law has not changed and it is only in very grave and limited circumstances (as outlined in Canon 844.4) that a non-Catholic (with the exception of members of the Orthodox Church) can receive Communion.
Communion is not a symbol of welcome and inclusion, it is the actual Body, Blood, Soul and Divinity of Christ. The Eucharist is God, not a symbol of God, not something that God is present in, but God Himself.